HVAC control using discrete-speed thermostats and run times

ABSTRACT

Methods of controlling air conditioning and HVAC units using a thermostat for a discrete-speed unit that include changing speed based on how long the unit operates at a particular speed. Speed may be increased if a unit operates for longer than a predetermined time at a particular speed, and speed may be reduced if the unit operated for less than a specific amount of time during the prior run. In different embodiments, single-stage thermostats may control units that operate at three speeds, and two-stage thermostats may control units that operate at three to five or more speeds. In addition, in some embodiments, outdoor coil temperature may be measured and considered in determining speed. Further, in some embodiments, maintaining continuous or repeated operation at a boost speed may be avoided. Energy savings and noise reduction may result.

RELATED PATENT APPLICATIONS

This patent application claims priority to Patent Cooperation Treaty(PCT) patent application PCT/US2010/37105 filed on Jun. 2, 2010, titled:HVAC CONTROL USING DISCRETE-SPEED THERMOSTATS AND RUN TIMES, having thesame inventors, which claims priority to U.S. Provisional PatentApplication No. 61/183,442, filed on Jun. 2, 2009, titled DISCRETE SPEEDTHERMOSTATS CONTROLLING VARIABLE SPEED HVAC UNITS, METHODS, APPARATUS,AND HEAT PUMPS, having the same inventors, the contents of both whichare incorporated herein by reference.

FIELD OF THE INVENTION

This Invention relates to heating, ventilating, and air conditioning(HVAC) equipment, controls for such equipment, and methods of making,adapting, improving, replacing, controlling, and distributing suchequipment, as well as HVAC units, systems, and buildings containing suchsystems. Particular embodiments concern controls for variable-speed HVACequipment.

BACKGROUND OF THE INVENTION

Heating, ventilating, and air conditioning equipment has been used toheat, cool, and ventilate buildings and other enclosed spaces wherepeople live and work. Air conditioning units and heat pumps have beenused that have had single-speed motors driving the compressors. Suchunits operated at one speed and cycled on and off under the control of athermostat to maintain space temperature, operating either at fullspeed, which was often noisy, or turned off.

In recent years, variable-speed drives have been used to drivecompressors as well as indoor and outdoor fans. Special thermostats havebeen used that have changed the speed of the compressor and fans tomaintain the set point temperature rather than cycling on and off. Sincethese units usually operate considerably below maximum speed, energyconsumption is reduced, resulting in greater overall efficiency.

Single-speed units have been replaced with variable-speed units, whichhas resulted in efficiency improvements as well as reductions in noise.In the past, however, such a unit replacement has necessitated thereplacement of the thermostat, wiring between the unit and thethermostat, or both, which has resulted in a greater cost ofreplacement, especially in comparison with replacement with anothersingle-speed unit that could reuse the old thermostat and thermostatwiring.

Two-speed or two-stage units (having two fixed non-zero speeds) havealso been used which have had an additional wire from the thermostat toselect between two non-zero compressor speeds, and often two non-zerofan speeds as well. Two-stage thermostats have typically called forstage one first, when the unit first turns on. In some configurations,the thermostat continued to call for stage one provided the measuredtemperature in the space moved towards the thermostat set pointtemperature. With such two-stage thermostats, however, if the measuredtemperature in the space moved away from the thermostat set pointtemperature, the thermostat called for stage two, increasing thecapacity of the unit. In such configurations, the more-efficient andquieter stage one was used unless the cooling or heating demand becameso large that the higher-capacity stage two was required in order toprevent the difference between the space temperature and the set pointtemperature from increasing.

In other two-stage configurations, however, the two-stage thermostatcalled for stage one if the measured temperature in the space wassufficiently close to the thermostat set point temperature, but calledfor stage two if the measured temperature in the space was sufficientlyfar away from the thermostat set point temperature. In suchconfigurations, if the unit or system was left on and the set pointtemperature remained unchanged, the thermostat called for stage onefirst, and only increased to stage two if stage one was inadequate tokeep the measured temperature in the space sufficiently close to thethermostat set point temperature. Again, in such configurations, insteady operation, the more-efficient and quieter stage one was usedunless the cooling or heating demand became so large that thehigher-capacity stage two was required in order to keep the temperaturein the space sufficiently close to the set point temperature. When theoperator first turned the unit on, however, or when the operator changedthe set point temperature, the measured temperature in the space mayhave initially been sufficiently far away from the thermostat set pointtemperature so as to demand stage two capacity. Thus, this configurationtypically resulted in more use of stage two, specifically, when theoperator adjusted the thermostat. But the system or unit was typicallymore responsive to operator adjustments.

Three-speed units with an additional thermostat wire have also beenused. Further, tandem multiple-capacity units have also been used withsimilar thermostats, which have had multiple single-speed compressors,for example. Such units have operated with one compressor running orwith multiple (e.g., two) compressors in operation to provide differentcapacities. With two compressors, for instance, as many as threedifferent capacities have been obtained where the two compressors wereof different sizes or ran at different speeds. The indoor fan, outdoorfan, or both, have been operated at different speeds depending on whichor how many compressors were in operation.

Two-speed or two-stage units and various other multi-capacity units haveprovided performance between that of single-speed units andvariable-speed units, regarding efficiency and noise, but again, inorder to replace a two-speed unit or another multi-capacity unit with avariable-speed unit, replacement of the thermostat and thermostat wiringwas typically required. Further, when single-speed, two-speed, or othermultiple-capacity units have been replaced with variable-speed units,for example, replacement of the indoor fan (i.e., blower), indoor fanmotor, expansion valve, or a combination thereof, often needed to bereplaced as well. In split systems, the complete indoor portion oftenneeded to be replaced in order to convert to a variable-speed system,which often substantially increased cost.

Needs or potential for benefit exist for equipment and methods thatallow single-speed and two-speed units (e.g., packaged units, spitsystem units, or just outdoor portions of split systems), as well asvarious multi-capacity units to be replaced with variable-speed units orunits having more speeds than the preexisting system offered withoutrequiring that the thermostat, thermostat wiring, indoor fan, indoor fanmotor, or a combination thereof (e.g., among other things), be replacedas well. Further, needs or potential for benefit exist for equipment andmethods that allow thermostats for discrete-speed (e.g., single-speed ortwo-speed) units to be used to control variable-speed HVAC units orunits having more speeds without requiring that the thermostat,thermostat wiring, or both, be replaced.

In addition, in the past, discrete-speed units, and especiallysingle-speed units, have often operated at a substantially highercapacity than necessary for the particular installation or theparticular conditions present. This has resulted in a unit operating ata high speed for a short time rather than, more efficiently and lessobtrusively, operating for a longer time at a lower speed. Consequently,needs or potential for benefit exist for equipment and methods thatallow HVAC units to detect when it is appropriate to operate at a lowerspeed for a longer time and to automatically do so. Furthermore, sinceconditions under which HVAC units operate change over time, often in afairly short time, needs or potential for benefit exist for equipmentand methods that allow HVAC units to return to a higher speed whenneeded to maintain the set point temperature, and to automatically do sowhen appropriate.

Moreover, traditional discrete-speed heat pumps have been used for bothcooling (e.g., in the summer) and heating (e.g., in the winter).Compressors have typically been operated at the same speed whether inthe heating or the cooling mode, and heat pumps have typically hadcorrespondingly similar capacity ratings whether in the cooling orheating mode. Even multiple-speed heat pumps and variable-speed heatpumps have traditionally operated at the same selection of (e.g.,compressor motor) speeds, or over the same range of speeds, whether inthe cooling or the heating mode.

In many climates, however, the demand for cooling or heating issubstantially unequal, For example, in warm climates, there may be amuch greater demand for cooling than for heating, and a heat pump thatis selected to meet the demand cooling may be oversized in the heatingmode. Such a unit may operate at a higher speed than needed in theheating mode, may cycle more frequently than desired, may be noisierthan necessary, may be less efficient than optimal in the heating mode,or a combination thereof, as examples. On the other hand, in colderclimates, there may be a much greater demand for heating than forcooling, and a heat pump that is selected to meet the demand heating maybe oversized in the cooling mode. Such a unit may operate at a higherspeed than needed in the cooling mode, may cycle more frequently thandesired, may be noisier than necessary, may be less efficient thanoptimal in the cooling mode, or a combination thereof, as examples.

As a result, needs or potential for benefit exist for equipment andmethods of adapting and distributing heat pumps to provide improvedefficiency performance in different climates where demand for coolingand heating are substantially unequal. In addition, needs or potentialfor benefit exist for heat pumps that are adapted to provide improvedefficiency performance in different climates where demand for coolingand heating are substantially unequal.

Further, needs or potential for benefit or improvement exist for methodsof manufacturing such heat pumps, HVAC equipment, and HVAC units, aswell as systems and buildings having such devices. Other needs orpotential for benefit or improvement may also be described herein orknown in the HVAC or control industries. Room for improvement existsover the prior art in these and other areas that may be apparent to aperson of ordinary skill in the art having studied this document.

References that may provide useful background information include WO2008/097743 (Chen et al.; PCT/US2008/052110), and US 2008/0041081(Tolbert; Ser. No. 11/464,586).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart illustrating an example of a method ofcontrolling an air conditioning unit or a heat pump operating in acooling mode using a single-stage thermostat, in which the unit selectsbetween a low speed, a high speed, and a boost speed;

FIG. 2 is a flow chart illustrating an example of a method ofcontrolling a heat pump operating in a heating mode using a single-stagethermostat, in which the unit selects between a low speed, a high speed,and a boost speed;

FIG. 3 is a flow chart illustrating an example of a method ofcontrolling an air conditioning unit or a heat pump operating in acooling mode using a two-stage thermostat, wherein stage one cooling iscalled for, and in which the unit selects between an L low speed, an Lmid speed, and an L high speed;

FIG. 4 is a flow chart illustrating an example of a method ofcontrolling an air conditioning unit or a heat pump operating in acooling mode using a two-stage thermostat, wherein stage two cooling iscalled for, and in which the unit selects between an H high speed and aboost speed;

FIG. 5 is a flow chart illustrating an example of a method ofcontrolling a heat pump operating in a heating mode using a two-stagethermostat, wherein stage one heating is called for, and in which theunit selects between an L low speed, an L mid speed, and an L highspeed; and

FIG. 6 is a flow chart illustrating an example of a method ofcontrolling a heat pump operating in a cooling mode using a two-stagethermostat, wherein stage two heating is called for, and in which theunit selects between an H high speed and a boost speed.

These drawings illustrate, among other things, examples of embodimentsof the invention. Other embodiments may differ.

SUMMARY OF PARTICULAR EMBODIMENTS OF THE INVENTION

This invention provides, among other things, various methods ofimproving an HVAC unit, methods of reducing the cost of replacingpreexisting HVAC hardware having a first number of discrete non-zerocompressor speeds with new HVAC hardware having a greater number ofcompressor speeds, methods of controlling an air conditioning unit tolimit use of electricity while maintaining space temperature within adesired range, apparatuses for cooling a space, methods of adapting anddistributing heat pumps to provide improved efficiency performance indifferent climates where demand for cooling and heating aresubstantially unequal, and heat pumps for providing improved efficiencyperformance in different climates where demand for cooling and heatingare substantially unequal.

Various embodiments provide, for example, as an object or benefit, thatthey partially or fully address or satisfy one or more needs, potentialareas for benefit, or opportunities for improvement described herein, orknown in the art, as examples. Certain embodiments provide, for example,equipment and methods that allow single-speed, two-speed, or three-speedunits to be replaced with variable-speed units or units having morespeeds without requiring that the thermostat, thermostat wiring, orboth, be replaced as well. In some embodiments, single-speed ormultiple-speed outdoor portions of split-systems may be replaced withouta need to replace the indoor portion, indoor fan, indoor fan motor, or acombination thereof, for example. Further, certain embodiments provideequipment or methods that allow thermostats for discrete-speed (e.g.,single-speed or two-speed) units to be used to control variable-speedHVAC units or units having more speeds without requiring that thethermostat, thermostat wiring, or both, be replaced.

In addition, a number of embodiments provide, as an object or benefit,equipment and methods that allow an HVAC unit to detect when it isappropriate to operate at a lower speed for a longer time and toautomatically do so. Furthermore, some embodiments provide equipment andmethods that allow HVAC units to return to a higher speed when needed tomaintain the set point temperature, and to automatically do so whenappropriate. Moreover, certain embodiments provide equipment and methodsof adapting and distributing heat pumps that provide improved efficiencyperformance in different climates where demand for cooling and heatingare substantially unequal. In addition, some embodiments provide heatpumps that are adapted to provide improved efficiency performance indifferent climates where demand for cooling and heating aresubstantially unequal.

Various embodiments provide, for example, as an object or benefit,methods of manufacturing such as heat pumps, HVAC equipment, and HVACunits, as well as systems and buildings having such devices. Otherobjects or benefits may also be described herein or known in the HVAC orcontrol industries. Room for improvement exists over the prior art inthese and other areas that may be apparent to a person of ordinary skillin the art having studied this document.

Specific embodiments of the invention include various methods ofcontrolling an air conditioning unit, for example, to reduce the use ofelectricity while maintaining space temperature within a desired range.Such a method may include, for example, certain acts, which may beperformed, for example, in the order listed. Such acts may include, in anumber of embodiments, receiving an on-signal from a thermostat locatedwithin the space, operating the unit at an operating speed, measuringhow long the unit operates, increasing the operating speed, receiving anoff-signal, and stopping operation of the unit. Such acts may alsoinclude receiving another on-signal from the thermostat, setting thecompressor speed, returning to the act of measuring how long the unitoperates, and repeating that act and the acts that follow.

In particular, the act of operating the unit at an operating speed mayinclude running a compressor motor driving a compressor at a compressorspeed, and running an evaporator fan motor at a blower speed. Theevaporator fan motor may drive an evaporator fan that moves indoor airthrough an evaporator and to the space. Further the act of operating theunit may include running a condenser fan motor at a condenser fan speed.The condenser fan motor may drive a condenser fan that moves outdoor airthrough a condenser, for example.

Further, after the act of measuring how long the unit operates, if theunit operates for longer than a predetermined maximum desired operatingtime, and if the unit is not already operating at a maximum operatingspeed, the method may include increasing the operating speed, and theact of increasing the operating speed may include increasing thecompressor speed. In addition the act (e.g., after receiving theoff-signal) of stopping operation of the unit, marks an end to anoperating cycle having a final compressor speed at the time theoff-signal is received. Furthermore, the act of stopping operation mayinclude turning off the compressor motor, turning off the evaporator fanmotor, and turning off the condenser fan motor.

Furthermore, after receiving an (e.g., another) on-signal from thethermostat located within the space, the method may include operatingthe unit at the operating speed. If the compressor speed was changedduring an immediately previous operating cycle, the compressor speed maybe set at the final compressor speed of the immediately previousoperating cycle. On the other hand, if the compressor speed was notchanged during the immediately previous operating cycle, if the unitoperated for less than a predetermined minimum desired operating timeduring the immediately previous operating cycle, and if the unit did notoperate at a minimum non-zero operating speed during the immediatelyprevious operating cycle, the method may include decreasing thecompressor speed from the final compressor speed of the immediatelyprevious operating cycle.

Moreover, if the compressor speed was not changed during the immediatelyprevious operating cycle, if the unit operated for more than thepredetermined minimum desired operating time during the immediatelyprevious operating cycle, and if the unit did not operate at a maximumnon-zero operating speed during the immediately previous operatingcycle, the compressor speed may be set at the final compressor speed ofthe immediately previous operating cycle. After such acts, the methodmay return to the act described above of measuring how long the unitoperates, and repeating that act and the acts that follow.

In particular embodiments, the available non-zero compressor speeds mayinclude, or consist of, a low speed, a high speed, and a boost speed,and the low speed may be the minimum non-zero speed, while the boostspeed is the maximum speed. Further, in some embodiments, such a methodmay further include, for example, an act of measuring a coil temperatureat the condenser. In various embodiments, for example, the act ofoperating the unit at the operating speed may include, for instance,selecting a higher compressor speed if the coil temperature exceeds afirst threshold temperature, and selecting a lower compressor speed ifthe coil temperature is below the first threshold temperature.

Further, in some embodiments, if the compressor speed was not changedduring the immediately previous operating cycle, and if the unitoperated at the maximum non-zero operating speed during the immediatelyprevious operating cycle, the operating speed may be decreased from theimmediately previous operating cycle, including decreasing thecompressor speed. In some embodiments, this may occur, for example, evenif the unit operated for longer than the predetermined minimum desiredoperating time during the immediately previous operating cycle, or incertain embodiments, even if the unit operated for longer than thepredetermined maximum desired operating time during the immediatelyprevious operating cycle.

Other specific embodiments of the invention include various methods ofcontrolling an HVAC unit having a compressor, that the HVAC unitoperates at multiple compressor speeds using a two-stage thermostat. Ina number of embodiments, the multiple compressor speeds include at leasttwo different non-zero compressor speeds for stage one, at least onenon-zero compressor speed for stage two, or both, for example. Further,in various embodiments, the at least two different non-zero compressorspeeds for stage one may include a highest compressor speed for stageone and a lowest compressor speed for stage one. Moreover, in someembodiments, the at least one non-zero compressor speed for stage twomay include a highest compressor speed for stage two, Further, invarious embodiments, the HVAC unit is configured to operate thecompressor using a signal from a two-stage thermostat and to select acurrent compressor speed from the multiple compressor speeds. Such amethod may include, for example, at least certain acts that include,when a current run signal is received from the thermostat, starting thecompressor, and performing certain acts of evaluating particularconditions and operating the compressor or changing the compressor speedbased on those conditions.

In particular, such acts may include evaluating whether the compressorstage changed during the immediate prior run (e.g., wherein theimmediate prior run had a prior run final compressor speed and a priorrun time), and if the compressor stage changed during the immediateprior run, such a method may include operating the compressor at thehighest compressor speed for stage one during the current run signal. Onthe other hand, if the compressor stage did not change during theimmediate prior run, and if the prior run final compressor speed was notthe lowest compressor speed for stage one, such a method may includeevaluating whether the prior run time was less than a predeterminedminimum desired operating time, for example, for the prior run finalcompressor speed. Further, if the prior run time was less than thepredetermined minimum desired operating time (e.g., for the prior runfinal compressor speed), the method may include operating the compressorat a speed during the current run signal that is (e.g., one step) lowerthan the prior run final compressor speed.

Another such act includes measuring a current speed operating timeduring the current run signal, and if the current compressor speed isnot already the highest compressor speed for stage two, and if thecurrent speed operating time is greater than a predetermined maximumdesired operating time for the current speed, increasing the compressorspeed (e.g., by one step) during the current run signal. Such a methodmay further include, after the current run signal is no longer receivedfrom the thermostat, stopping the compressor and repeating the aboveacts when the run signal is restored.

In a number of embodiments, the highest compressor speed for stage twois higher than (or in some embodiments, higher than or equal to) thehighest compressor speed for stage one. Further, in a number ofembodiments, the highest compressor speed for stage one is higher thanthe lowest compressor speed for stage one. Moreover, in someembodiments, the HVAC unit may have a two-speed indoor air fanconfigured to operate at a low speed and at a high speed, and the methodmay include, for instance, operating the indoor air fan at the low speedwhen the compressor is operating at the at least two different non-zerocompressor speeds for stage one. Further, in certain embodiments, such amethod may include for example, operating the indoor air fan at the highspeed when the compressor is operating at the at least one non-zerocompressor speed for stage two.

Still further, in certain embodiments, the HVAC unit has an outdoor airfan that operates at multiple non-zero speeds. These speeds may include,for example, at least a first outdoor air fan speed and a second outdoorair fan speed. In a number of embodiments, the method may include, forinstance, operating the outdoor air fan at the first outdoor air fanspeed when the compressor is operating at the lowest compressor speedfor stage one. Furthermore, various embodiments may include operatingthe outdoor air fan at the second outdoor air fan speed when thecompressor is operating at the highest compressor speed for stage two.Even further, in a number of embodiments, the second outdoor air fanspeed may be greater than the first outdoor air fan speed.

Still other specific embodiments of the invention include variousmethods of controlling an HVAC unit (e.g., having a compressor), thatoperates the compressor at multiple compressor speeds, the multiplecompressor speeds including an L low speed, at least one (e.g., one ormultiple) L mid speed, an L high speed, an H high speed, and a boostspeed. In such embodiments, the HVAC unit may be configured to operatethe compressor using a signal from a two-stage thermostat, for example,and to select a current compressor speed from the multiple compressorspeeds. Such a method may include, for example, at least certain acts,which may include, when a current run signal is received from thethermostat, starting the compressor, and evaluating whether thethermostat is calling for stage one or stage two.

If the thermostat is calling for stage one, such a method may include anact of evaluating whether the thermostat called for stage two after astart of an immediate prior run, and if the thermostat called for stagetwo after the start of the immediate prior run, the method may includeoperating the compressor at the L High speed during the current runsignal. Further, if the thermostat is calling for stage one, and if thethermostat has not called for stage two since before the immediate priorrun, the method may include an act of evaluating whether the compressorspeed changed during the immediate prior run (e.g., wherein theimmediate prior run had a prior run final compressor speed and a priorrun time). If the compressor speed changed during the immediate priorrun, the method may include operating the compressor at the prior runfinal compressor speed during the current run signal.

Furthermore, if the thermostat is calling for stage one, if thethermostat has not called for stage two since before the immediate priorrun, and if the compressor speed did not change during the immediateprior run, such a method may include an act of evaluating whether theprior run final compressor speed was the L low speed, the L mid speed(or one of the L mid speeds), or the L high speed. If the prior runfinal compressor speed was the L mid speed (or one of the L mid speeds),such a method may include evaluating whether the prior run time was lessthan a predetermined L mid speed minimum desired operating time If theprior run time was less than the predetermined L mid speed minimumdesired operating time, the method may include decreasing the compressorspeed during the current run signal (e.g., operating the compressor atthe L low speed during the current run signal).

Even further, if the thermostat is calling for stage one, if thethermostat has not called for stage two since before the immediate priorrun, if the compressor speed did not change during the immediate priorrun, and if the prior run final compressor speed was the L high speed,such a method may include an act of evaluating whether the prior runtime was less than a predetermined L high speed minimum desiredoperating time. If the prior run time was less than the predetermined Lhigh speed minimum desired operating time, such a method may include anact of operating the compressor at the L mid speed (e.g., one of the Lmid speeds) during the current run signal. Moreover, if the thermostatis calling for stage two, and if the thermostat did not call for stagetwo during the immediate prior run, such a method may include operatingthe compressor at the H high compressor speed during the current runsignal.

Still further, such a method may include measuring a current speedoperating time during the current run signal, and if the currentcompressor speed is the L low speed, and if the current speed operatingtime is greater than a predetermined L low speed maximum desiredoperating time, the method may include an act of increasing thecompressor speed (e.g., to the L mid speed or one of multiple L midspeeds) during the current run signal. Further, if the currentcompressor speed is the L mid speed (e.g., one of the L mid speeds), andif the current speed operating time is greater than a predetermined Lmid speed maximum desired operating time, such a method may include anact of increasing the compressor speed, for example, to the L highspeed, during the current run signal. Further still, if the currentcompressor speed is the H high speed, and if the current speed operatingtime is greater than a predetermined H high speed maximum desiredoperating time, such a method may include increasing the compressorspeed to the boost speed during the current run signal. In a number ofembodiments, after the current run signal is no longer received from thethermostat, such a method may further include acts of stopping thecompressor and repeating the above acts when the run signal is restored.

In certain embodiments, a method may include, for example, when thecurrent run signal is first received from the thermostat, acts ofstarting the compressor, ramping the compressor up to a start speed, andoperating the compressor for a predetermined desired start time at thestart speed. In some embodiments, for example, the start speed is alwayssubstantially the same regardless of the prior run final compressorspeed. Further, in a number of embodiments, the HVAC unit has avariable-speed drive for the compressor, and the HVAC unit operates thecompressor at only a limited whole number of steady compressor speeds.The steady compressor speeds may include, for example, the L low speed,the (e.g., at least one) L mid speed, the L high speed and the H highspeed. In particular embodiments, the L mid speed (or L mid speeds) maybe higher than the L low speed, the L high speed may be higher than theL mid speed (or L mid speeds), the H high speed may be higher than the Lhigh speed, and the boost speed may be higher than the H high speed, forexample. In certain embodiments, the method may include, for example,operating the compressor at no steady speeds other than the L low speed,the L mid speed (or L mid speeds), the L high speed, the H high speed,the boost speed, and the start speed.

In some embodiments, the HVAC unit may have a two-speed indoor air fan,for example, configured to operate at a low speed and at a high speed,and the method may include, for instance, operating the indoor air fanat the low speed when the compressor is operating at the L low speed,and operating the indoor air fan at the low speed when the compressor isoperating at the L mid speed (or L mid speeds). Such a method may alsoinclude operating the indoor air fan at the high speed when thecompressor is operating at the H high speed, and operating the indoorair fan at the high speed when the compressor is operating at the boostspeed.

Further, in some embodiments, such a method may further include, forexample, if the compressor speed did not change during the immediateprior run, evaluating whether an outdoor temperature parameter is beyonda first threshold. If the outdoor temperature parameter is beyond thefirst threshold, such a method may include operating the compressor at ahigher speed during the current run signal. In particular embodiments,the HVAC unit has an outdoor coil and the outdoor temperature parameteris a temperature of the outdoor coil. In some embodiments, such a methodmay further include an act of varying the boost speed as a function ofthe outdoor temperature parameter. Moreover, in some embodiments, such amethod may further include, for example, if the thermostat is callingfor stage two, if the thermostat called for stage two during theimmediate prior run, and if the compressor speed did not change duringstage two of the immediate prior run, an act of operating the compressorat the H high speed during the current run signal regardless of theoutdoor temperature parameter.

In some methods, if the thermostat is calling for stage two, if thethermostat called for stage two during the immediate prior run, and ifthe compressor speed changed during stage two of the immediate priorrun, the method may include an act of operating the compressor at theboost speed during the current run signal, In some embodiments, this maybe done, for example, without first operating the compressor at the Hhigh speed for the predetermined H high speed maximum desired operatingtime. Further, in some embodiments, if the thermostat is calling forstage two, if the thermostat called for stage two during the immediateprior run, and if the compressor speed did not change during stage twoof the immediate prior run, a method may include operating thecompressor at the H high speed during the current run signal. Inparticular embodiments, for instance, the act of operating thecompressor during the current run signal at the H high speed may beperformed regardless of the prior run time.

In addition, various other embodiments of the invention are alsodescribed herein, and other benefits of certain embodiments may beapparent to a person of ordinary skill in the art.

DETAILED DESCRIPTION OF EXAMPLES OF EMBODIMENTS

The subject matter described herein includes, as examples, variousapparatuses for cooling a space, HVAC units, heat pumps, HVAC equipment,HVAC controllers, and the like. As used herein, the term “HVAC unit”includes air conditioning units and heat pumps, which may be packagedunits or split systems, for example. Further, as used herein, the term“HVAC unit” includes outdoor portions of split systems (e.g., absent theindoor portion, thermostat, or both). Moreover, other embodimentsinclude various buildings containing such devices, companies performingone or more of the methods described herein, computer-readable storagemedia, computers programmed to perform at least one method describedherein, and computer software, as examples. Methods described hereininclude methods of improving HVAC units, methods of replacing HVACequipment (e.g., which may provide better performance, efficiency, orboth); methods of controlling HVAC units (e.g., air conditioning units),methods of providing HVAC equipment described herein, and methods ofadapting and distributing HVAC equipment (e.g., heat pumps), forinstance, for use in different climates.

In a number of embodiments, a thermostat for (i.e., designed for) adiscrete-speed (e.g., one, two, or three speed) unit is used to controla variable-speed unit, for example, which may provide an increasednumber of available speeds, may improve efficiency, or both, asexamples. In a number of embodiments, use of a thermostat for adiscrete-speed unit, use of existing wiring for such a thermostat, useof an existing indoor portion of a split-system, use of an existingindoor fan, use of an existing indoor fan motor, or a combinationthereof, may reduce installation cost, particularly where adiscrete-speed unit is being replaced with a variable-speed unit, forexample.

In various embodiments, a controller measures how much time passesbetween changes in thermostat signals or how long a unit operates (e.g.,before shutting off), and these measurements are used (e.g., by thecontroller) to determine the speed at which to operate the compressor,for example. Additionally, in certain embodiments, an outdoortemperature, such as an outdoor coil or heat exchanger temperature, maybe used to select between available speeds, for instance. In otherembodiments, however, temperature may not be measured or used todetermine speed, and the control algorithm may work satisfactorilywithout measuring or using an outdoor temperature. Further, in someembodiments, heat pumps are configured to operate at reduced speeds ineither a cooling or a heating mode in order to provide improvedefficiency performance, for example, in climates where demand forcooling and heating are substantially unequal.

In particular embodiments, various apparatuses for cooling a space(e.g., within a building) may include, for example, a compressor, avariable-speed compressor motor for driving the compressor (e.g., indriving relation to the compressor), a variable-speed drive for poweringthe compressor motor (e.g., a variable-frequency drive or avariable-voltage DC power supply), and a controller for controlling thevariable-speed drive and thereby controlling speed of the compressormotor, as examples. Many such embodiments may include, in addition,other components of such an apparatus as well. Variable-speed drives,motors, and systems may provide continuously-variable speeds, forexample, over a range of speeds. In some embodiments, however,particular speeds across the range may be selected, which may be spacedapart, for example, and may avoid points of resonance, for instance. Insome embodiments, the range may be divided into about 20 particularspeeds, for instance, which may be fairly evenly spaced, and the motormay be ramped (i.e., gradually, but continuously changed, for instance,at a constant rate of change of speed) between these particular speedsand held at the particular speeds. In a number of embodiments, for aparticular application, a subset of these particular speeds may be usedor selected and made available for use under appropriate demandconditions.

In some embodiments, the controller may be configured (e.g., viaprogramming or software) to operate the variable-speed drive at multiplenon-zero compressor speeds using an on-off thermostat signal from athermostat configured to control a single-speed HVAC unit by providingan on-off thermostat signal, for example. As used herein, if a device is“configured” to perform a certain task or function, the term“configured” means that the device has been adapted specifically toperform that particular task or function, not merely that the devicecould be used for that particular task or function if doing so had beencontemplated. As used herein, a controller is “configured” to perform aparticular task or function if the controller has been programmed withinstructions that will, if executed, perform that specific task orfunction. A controller simply being made to control similar equipmentand being capable of being programmed to perform the particular task orfunction is not enough, absent the software instructions to do so orother specific adaptation to accomplish the particular task or functionrecited.

Further, in a number of embodiments, the controller may be configured tomeasure time between changes in the on-off thermostat signal, forinstance, and select the compressor speed based on the time betweenchanges in the on-off thermostat signal, for example. In someembodiments, the controller may be configured, for example, to operatethe variable-speed drive at two non-zero compressor speeds. As usedherein, a controller is configured to perform a task or act if thecontroller is configured to output a signal that instructs another pieceof equipment to perform that task or act. Further, in certainembodiments, the controller may be configured, for another example, tooperate the variable-speed drive at more than two non-zero compressorspeeds using at least two on-off thermostat signals from a thermostatconfigured to control a two-speed HVAC unit by providing two on-offthermostat signals, as another example. In particular embodiments, thecontroller may be configured, for instance, to operate thevariable-speed drive at three non-zero compressor speeds, at fournon-zero compressor speeds, at five non-zero compressor speeds, at sixnon-zero compressor speeds, at seven non-zero compressor speeds, or atmore than seven non-zero compressor speeds, as examples.

In some embodiments, the controller may be configured, for example, toselect the compressor speed utilizing a time between a thermostat onsignal and a thermostat off signal, utilizing a time between athermostat on signal and a present time, or both, as examples. Forinstance, in some embodiments, the controller may be configured toselect a lower compressor speed if a time that the compressor has runwas below a minimum time threshold. For example, if during one cycle(e.g., on-signal from the thermostat), the compressor runs less than theminimum time before the thermostat calls for the unit to shut off, thenthe controller may select a lower compressor speed the next time thethermostat calls for the unit to turn on. In different embodiments, sucha minimum time may be, for example, about 10 minutes, about 12 minutes,about 14 minutes, about 17 minutes, about 20 minutes, about 24 minutes,about 29 minutes, about 35 minutes, about 42 minutes, about 51 minutes,or about 62 minutes, as examples. As used herein, unless indicatedotherwise, “about” means plus or minus 10 percent.

Further, in some embodiments, the controller may be configured, foranother example, to select a higher compressor speed if a time that thecompressor has run exceeds a maximum time threshold. For example, ifduring operation at one steady non-zero speed, the compressor runs morethan the maximum time before the thermostat calls for the unit to shutoff, then the controller may change the compressor speed (e.g., duringthat same on-signal from the thermostat) to a higher compressor speed.In some embodiments, the compressor may maintain that higher speed thenext time the thermostat calls for the unit to turn on, for example. Indifferent embodiments, such a maximum time may be, for example, about 21minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40minutes, about 45 minutes, about 50 minutes, about 55 minutes, about 60minutes, about 70 minutes, or about 85 minutes, as examples.

In particular embodiments, the controller may be configured to selectthe compressor speed utilizing a time between a thermostat off signaland a thermostat on signal. For example, in some embodiments, if thetime between the last thermostat off signal and the current thermostaton signal exceeds a longer off-period threshold, then the controller mayselect a lower speed (e.g., because less capacity may be needed tomaintain the set point temperature). On the other hand, if the timebetween the last thermostat off signal and the current thermostat onsignal is less than a shorter off-period threshold, then the controllermay select a higher speed (e.g., because more capacity may be needed tomaintain the set point temperature or because a user may have changedthe thermostat set point temperature and may want or expect a rapidcorresponding change in temperature of the occupied space). In differentembodiments, such a longer off-period threshold may be, for instance,about 40 minutes, about 45 minutes, about 50 minutes, about 60 minutes,about 70 minutes, about 80 minutes, about 90 minutes, about 100 minutes,about 120 minutes, or about 140 minutes, as examples. In variousembodiments, a shorter off-period threshold may be, for instance, about5 minutes, about 6 minutes, about 8 minutes, about 10 minutes, about 12minutes, about 15 minutes, about 18 minutes, about 21 minutes, about 25minutes, or about 30 minutes, as examples.

In various embodiments, a temperature sensor may be included or providedwhich may be positioned and configured to measure an outdoortemperature, for instance. In some embodiments, the controller may beconfigured, for example, to select the compressor speed based (e.g.,among other things) on, or using, the outdoor temperature. In particularembodiments, the temperature sensor may be positioned and configured tomeasure an outdoor heat exchanger temperature, for example, and thecontroller may be configured to select the compressor speed based on theoutdoor heat exchanger temperature. Specifically, in some embodiments,the controller may be configured, for example, so that when the HVACunit is operating in a cooling mode, the controller will select a highercompressor speed if the outdoor heat exchanger temperature exceeds afirst (e.g., preset) temperature threshold. In various embodiments, thefirst threshold temperature may be approximately 80 degrees,approximately 89 degrees, approximately 92 degrees, or approximately 95degrees F. (i.e., Fahrenheit), as examples. As used herein,“approximately”, when referring to temperature, means within plus orminus 5 degrees F.

Further, in some embodiments, the controller may be configured, forexample, so that when the HVAC unit is operating in a heating mode, thecontroller will select a higher compressor speed if the outdoor heatexchanger temperature is below a second preset temperature threshold. Indifferent embodiments, the second threshold temperature may beapproximately 30 degrees, approximately 34 degrees, approximately 37degrees, approximately 40 degrees approximately 50 degrees, orapproximately 60 degrees (F.), as examples.

In some embodiments, the apparatus may be an outdoor portion of a splitsystem HVAC system, while in other embodiments, the apparatus may be apackaged HVAC unit or may include both indoor and outdoor portions of asplit HVAC system. In a number of embodiments, the apparatus includes,for example, an outdoor heat exchanger (e.g., which acts as a condenserwhen operating in a cooling mode and may act as an evaporator whenoperating in a heating mode), an outdoor fan positioned and configuredto move outdoor air through the outdoor heat exchanger, an outdoor fanmotor, an outdoor portion housing, or a combination thereof, forexample. In some embodiments, the outdoor fan motor is a multiple-speedmotor and in particular embodiments, the controller may be configured,for instance, to operate the outdoor fan motor at multiple non-zerooutdoor fan speeds. In certain embodiments, for example, the apparatusmay include a variable-speed drive for the outdoor fan motor, and thecontroller may be configured, for instance, to operate the outdoor fanmotor at multiple non-zero outdoor fan speeds. In some embodiments, forexample, there may be a different outdoor fan speed corresponding toeach available compressor speed.

In some embodiments (e.g., packaged units or split systems with bothindoor and outdoor portions), the apparatus further includes, forexample, an indoor air heat exchanger (e.g., which acts as an evaporatorwhen operating in a cooling mode and may act as a condenser whenoperating in a heating mode), an indoor air fan positioned andconfigured to move indoor air through the indoor air heat exchanger, anindoor air fan motor, or a combination thereof, for instance. In someembodiments, the indoor air fan motor may be a multiple-speed motor andthe controller may be configured, for example, to operate the indoor airfan motor at multiple speeds. In particular embodiments, the apparatusmay include, for example, a variable-speed drive for the indoor air fanmotor, and the controller may be configured, for instance, to operatethe indoor air fan motor at multiple speeds. In some embodiments, forexample, there may be a different indoor fan speed corresponding to eachavailable compressor speed.

In a range of embodiments, the controller may include various hardwarecomponents such as one or more circuit boards, microprocessors, memory,logic controllers, user interface devices, displays, and the like. Inparticular embodiments, the controller may include, for example, aninverter board, a relay board or interface board electrically connectedbetween the inverter board and the thermostat (e.g., for a single-speedor two-speed unit), or both, for example.

In an example of an embodiment, the inverter board input and output tothe relay (interface) board, for single stage and two-stage thermostatapplications are as follows:

Terminals Pin 1 Y1 Cool single stage input Pin 2 Y2 Cool two stage inputPin 3 W2 Heat output Pin 4 O Heat/Cool input Pin 5 Spare 1 Spare outputPin 6 Spare 2 Spare output Pin 7 L Fault code output Pin 8 Spare Spareinput Pin 9 Spare Spare Output Pin 10 GND Board ground

Control outputs may be able to source and sink 5 mA minimum and may be5VDC logic. In this embodiment, the Y1 Input is active logic, level high(5VDC). This is a control input for the single stage cooling mode inthis embodiment. Further, the Y2 Input is active logic, in thisembodiment, level high (5VDC), and is a control input for the secondstage cooling mode. Y1 input, in this embodiment, will also be logiclevel high at this time. Moreover, W2 Output is active logic, level high(5VDC). This output is active logic level high when the control hasdetermined there is a defrost cycle active, in this embodiment.Furthermore, O Input is active logic, level high (5VDC). This is acontrol input for the reversing valve operation in this embodiment. Whenthis input is active logic level high, the reversing valve is energized.This input is active logic level high for cooling mode.

Further, Spare 1 output is active logic, level high (5VDC). This outputis a spare control output that is not defined (yet) in this embodiment.In addition, Spare 2 output is active logic, level high (5VDC). Thisoutput is a spare control output that is not defined yet in thisembodiment. Even further, L Output is normally high. This output is usedto inform an external interface board of faults that have occurred. Thisoutput will output low pulses in this embodiment. The pulse width willbe 1 mSec with a 1 mSec high time and a minimum of 200 mSec high timebetween fault codes in this embodiment.

In some embodiments, the interface board may be configured, for example,to read 24 V AC signals from the thermostat, to communicate with theinverter board using 5 V signals, or both, for instance. In certainembodiments, the interface board may be configured, for example, tocommunicate with the inverter board through a communications bus,through an RS-232 line, or through an RS-485 line, as examples. In someembodiments, the relay or interface board may have a display, may beused to perform diagnostic functions, or both, as examples.

Various embodiments of the subject matter described herein are HVACunits, HVAC systems, or buildings comprising an apparatus, HVAC unit, orHVAC system as described herein. Buildings may include one or morefloor, walls, and ceiling, which may fully or partially enclose a spacethat may be cooled or heated by an apparatus, HVAC unit, or HVAC systemas examples. In some embodiments, a building may substantially enclose aspace, for example. As used herein, “substantially” enclosing a spacemeans blocking at least 90 percent of the surface area surrounding thespace. In a situation where HVAC equipment, for example, is beingreplaced, wiring for a preexisting thermostat may run through the floor,walls, or between the ceiling and a roof, as examples. Access to suchwiring may be limited or difficult and replacement of the wiring with adifferent type of wiring may be difficult, expensive, or both, in manysituations.

A number of embodiments include heat pumps that are adapted forproviding improved efficiency performance in different climates wheredemand for cooling and heating are substantially unequal. As usedherein, “unequal” means unequal by at least 5 percent, and“substantially unequal” means unequal by at least 15 percent. In varioussuch embodiments, such a heat pump may be an outdoor portion of a splitsystem HVAC system, may include an indoor portion of a split system HVACsystem, or may be a packaged HVAC unit, as examples. In differentembodiments, these heat pumps may include some or all of the features orfunctionality described above, or may lack such features orfunctionality. For example, in some embodiments, such a heat pump mayinclude, for instance, a compressor, a compressor motor (e.g.,mechanically connected to the compressor to drive the compressor), and avariable-speed drive (e.g., electrically connected to the compressormotor to power the compressor motor and change speed of the compressormotor). Such a heat pump may also include a controller (e.g., incommunication with or in control of the variable-speed drive), which mayinclude instructions (e.g., programming or software) to operate thecompressor motor at multiple different speeds in each of a cooling modeand a heating mode. As used herein, if speeds are indicated to be“different” (i.e., with no modifier before “different”) then the speedsare at least five percent different. Moreover, as used herein, if speedsare indicated to be “substantially different” then the speeds are atleast 15 percent different.

These embodiments may also include at least one user input device whichmay be arranged to allow a person to select at least one operating speedof the compressor motor in the cooling mode and arranged to allow theperson to select at least one operating speed of the compressor motor inthe heating mode. The user input device may be, for example, one or moredials, knobs, buttons, keyboards, keypads, jumpers or dip switches, orthe like, as examples, and may include a display, in some embodiments.In various embodiments, the controller and the user input device may beconnected and configured so that the person can select a substantiallydifferent operating speed of the compressor motor in the cooling modethan the operating speed of the compressor motor in the heating modesuch that all selected speeds of the compressor motor in the coolingmode or all selected speeds of the compressor motor in the heating modeare substantially below a maximum capable compressor motor speed for theheat pump. As used herein, at least when referring to speed, “below”means at least five percent below, and “substantially below” means atleast 15 percent below. The selected speeds are speeds that are actuallyused (i.e., in a steady state condition or other than ramping through).The maximum capable compressor motor speed is the greatest speed thatcan be selected, for example, the rated speed of the motor, drive, orother limiting component.

In a number of embodiments, multiple (e.g., some, all except for one,all except for the lowest speed, or all) selected speeds of thecompressor motor in the cooling mode or multiple (e.g., some, all exceptfor one, all except for the lowest speed, or all) selected speeds of thecompressor motor in the heating mode (or both) are reducedproportionally from the maximum capable compressor motor speed for theheat pump. In some embodiments, the lowest speed may remain unchanged,and the other speeds may be reduced proportionally from the maximumcapable compressor motor speed for the heat pump, for instance. As usedherein, “proportionally”, when referring to speeds, means proportionalwithin five percent. Moreover, as used herein, “substantiallyproportionally”, when referring to speeds, means proportional within 15percent. Further, in some embodiments, at least one selected speed ofthe compressor motor may be substantially below a maximum capablecompressor motor speed for the heat pump. Even further, in particularembodiments, at least one selected speed of the compressor motor (e.g.,that is substantially below a maximum capable compressor motor speed forthe heat pump) may provide a higher efficiency of the heat pump than themaximum capable compressor motor speed.

In some embodiments, the heat pump may be configured for the inputdevice to be used to select at least one operating speed of thecompressor motor in the cooling mode and in the heating mode before theheat pump is shipped to the installation site, before the heat pump isinstalled, or specifically, in some embodiments, in a factory where theheat pump is assembled, as examples. In other embodiments, the heat pumpmay be configured for the input device to be used to select at least oneoperating speed of the compressor motor in the cooling mode and in theheating mode when the heat pump is installed (e.g., by the installer).Moreover, in particular embodiments, the building owner or hisrepresentative may use the input device to set one or more speed, forexample, at the preference of the owner or occupant of the building.

In some embodiments, the controller may be configured, for example, tooperate the compressor motor at a first number of different selectedspeeds in the cooling mode and a second number of different selectedspeeds in the heating mode. In some embodiments, the first number andthe second number are both whole numbers. In a number of embodiments,the controller may be configured, for example, to proportionally lowermultiple (e.g., some, all except for one, all except for the lowestspeed, or all) of the first number of different selected speeds in thecooling mode (e.g., for climates where more heating capacity is neededthan cooling capacity). On the other hand, in some embodiments, thecontroller may be configured, for example, to proportionally lowermultiple (e.g., some, all except for one, all except for the lowestspeed, or all) of the second number of different selected speeds in theheating mode (e.g., for climates where more cooling capacity is neededthan heating capacity). In many embodiments, the controller may beconfigured to operate the heat pump in either of these ways, dependingon what is appropriate for the climate where the heat pump is to beused.

In various embodiments, the heat pump may be operated at the same numberof speeds in the cooling mode as in the heating mode (e.g., the firstnumber is equal to the second number), but these speeds may differ orsubstantially differ depending on whether the heat pump is operating inthe cooling mode or the heating mode. On the other hand, in someembodiments, the heat pump may operate at a greater number of speeds inthe cooling mode than in the heating mode (e.g., the first number may begreater than the second number), or the heat pump may operate at agreater number of speeds in the heating mode than in the cooling mode(e.g., the second number may be greater than the first number). Invarious embodiments, the first number is greater than two, the firstnumber is less than ten, the second number is greater than two, thesecond number is less than ten, or a combination thereof, as examples.In certain embodiments, the first number, the second number, or both,may be, for example, 3, 4, 5, 6, 7, 8, or 9.

In a number of embodiments, the controller may be configured to lowermultiple (e.g., some, all except for one, all except for the lowestspeed, or all) selected speeds in the cooling mode proportionally to areduction of rated capacity in the cooling mode, may be configured tolower multiple (e.g., some, all except for one, all except for thelowest speed, or all) selected speeds in the heating mode proportionallyto a reduction of rated capacity in the heating mode, or both, asexamples. Further, in some embodiments, the controller may be configuredto operate the outdoor fan motor of the heat pump at different speedsfor different compressor speeds, or specifically to operate the outdoorfan motor of the heat pump at a speed that is proportional to aconcurrent compressor speed. Similarly, in some embodiments, thecontroller may be configured to operate the indoor fan motor of the heatpump at different speeds for different compressor speeds, orspecifically, to operate the indoor fan motor of the heat pump at aspeed that is proportional to a concurrent compressor speed.

In addition to apparatuses, such as HVAC equipment, HVAC units, heatpumps, HVAC systems, HVAC controllers, and buildings, variousembodiments of the subject matter are or include various methods, whichinclude (e.g., in any order except where order is apparent or isindicated) at least certain acts. For example, a number of embodimentsare or include various methods of improving an HVAC unit. Such methodsmay include, for instance, acts of replacing at least a compressor motoror at least a compressor and a compressor motor in an outdoor portion ofa split-system HVAC unit. In some embodiments, additional components, upto and including the complete outdoor portion of the unit may bereplaced. A number of embodiments may include, for example, providing atleast a new compressor, a new compressor motor, a new variable-speeddrive for the compressor motor, and a new controller. Some embodimentsmay further include connecting refrigerant lines between the newcompressor of the split-system HVAC unit and a preexisting indoorportion of the split-system HVAC unit, which may include, for instance,a preexisting indoor heat exchanger, a preexisting indoor fan positionedand configured to move indoor air through the indoor heat exchanger, apreexisting indoor fan motor, and a preexisting indoor portion housing,as examples.

In a number of cases, the preexisting indoor fan motor may be adiscrete-speed motor having a first number of discrete non-zerooperating speeds. For instance, the first number may be no more thantwo. In other words, the preexisting indoor fan motor may be asingle-speed motor or a two-speed motor, in many instances. In otherembodiments, the preexisting indoor fan motor may be a three-speedmotor, as another example.

The preexisting HVAC unit may further include, for example, apreexisting thermostat configured to control the preexistingdiscrete-speed HVAC unit, for instance, by providing an on-offthermostat signal for each discrete speed. Various embodiments ofmethods, which are described herein, include acts of reusing preexistingelectrical wiring to the preexisting thermostat, connecting thepreexisting electrical wiring to the new controller, or both, asexamples. Further, various methods may include operating the HVAC unitat a second number of non-zero compressor speeds using the on-offthermostat signal from a thermostat configured to control adiscrete-speed HVAC unit by providing an on-off thermostat signal foreach discrete speed. In different embodiments, this thermostat may bethe preexisting thermostat, for example, or may be a different (e.g.,new) thermostat configured to control similar units. In someembodiments, the second number may be at least one more than the firstnumber, thus increasing the number of speeds that the unit can operateat. Further, a number of methods may include measuring time betweenchanges in the on-off thermostat signal, selecting the compressor speedbased (e.g., among other things) on the time between changes in theon-off thermostat signal, or both.

Some methods may include replacing an outdoor portion of a split-systemHVAC unit, for instance, which may include, as might be expected,providing a new outdoor portion of the split-system HVAC unit. Such anoutdoor portion may include, for example, (e.g., in addition to some orall of the new components mentioned above), a new outdoor heatexchanger, a new outdoor fan positioned and configured to move outdoorair through the outdoor heat exchanger, a new outdoor fan motor, a newoutdoor portion housing, or a combination thereof, as examples.

In some embodiments, the preexisting indoor fan motor may be asingle-speed motor, for example, having one discrete non-zero operatingspeed, and the thermostat may be configured, for example, to control thepreexisting HVAC unit by providing an on-off thermostat signal forturning the HVAC unit on or off. In particular embodiments, the methodincludes operating the HVAC unit at more than one non-zero compressorspeed using the on-off thermostat signal from the thermostat and, in anumber of embodiments, selecting the compressor speed based on the timebetween changes in the on-off thermostat signal. On the other hand, insome embodiments, the preexisting indoor fan motor is a two-speed motorhaving two discrete non-zero operating speeds, and the thermostat may beconfigured, for example, to control the preexisting discrete-speed HVACunit by providing two distinct on-off thermostat signals for turning theHVAC unit on or off and for selecting between a high and a low speed,for instance. In certain embodiments, the method may include operatingthe HVAC unit at more than two non-zero compressor speeds using theon-off thermostat signals from the two-speed or two-stage thermostat andselecting the compressor speed based on (in some embodiments, amongother things) the on-off thermostat signals and the time between changesin the on-off thermostat signal.

In some embodiments, the act of selecting the compressor speed based onthe time between changes in the on-off thermostat signal may include,for example, selecting a lower compressor speed if a time that thecompressor has run is below a minimum time threshold, selecting a highercompressor speed if a time that the compressor has run exceeds a maximumtime threshold, or both, as examples. Further, in some embodiments, theact of operating the HVAC unit at the second number of non-zerocompressor speeds may include operating the outdoor fan motor atmultiple non-zero outdoor fan speeds (e.g., two, three, four, five, ormore different speeds).

Various methods may further include, for example, acts of measuring anoutdoor temperature and selecting the compressor speed based on (e.g.,among other things) the outdoor temperature. In some embodiments, theoutdoor temperature may be a heat exchanger temperature, for example.For instance, in a number of embodiments, when the HVAC unit isoperating in a cooling mode, the act of selecting the compressor speedbased on the outdoor temperature may include selecting a highercompressor speed if the outdoor temperature exceeds a first presettemperature threshold. In addition, or instead, in some embodiments,when the HVAC unit is operating in a heating mode, the act of selectingthe compressor speed based on the outdoor temperature may includeselecting a higher compressor speed if the outdoor temperature is belowa second preset temperature threshold. In embodiments where the outdoortemperature is a coil temperature, a certain amount of time may beallowed to pass after the compressor starts before the temperature ismeasured or considered, in order to allow steady state conditions to bereached. This certain amount of time may be, for example, about fiveminutes, about six minutes, about seven minutes, about eight minutes,about nine minutes, about ten minutes, about eleven minutes, abouttwelve minutes, about thirteen minutes, or about fifteen minutes, asexamples. In other embodiments, temperature readings may be disregardedunless changes between successive readings fall below a threshold.Further, in other embodiments, refrigerant pressure (e.g., at theoutdoor heat exchanger), refrigerant temperature (e.g., after theoutdoor heat exchanger, or both, may be measured instead of (or inaddition to) air or coil temperature, as other examples.

Another example of a method of improving an HVAC unit includes, forexample, providing new HVAC hardware for a split-system HVAC system, thenew HVAC hardware including, for example, at least a new compressor, anew compressor motor, a new variable-speed drive for the compressormotor, and a new controller. In this embodiment, the new controller maybe configured to operate the new variable-speed drive at a second numberof non-zero compressor speeds using at least one on-off thermostatsignal from a thermostat configured to control a discrete-speed HVACunit by providing the on-off thermostat signal for each discrete speed,measure time between changes in the on-off thermostat signal, and selectthe compressor speed based on the time between changes in the on-offthermostat signal, as examples. Further, this embodiment may includeinstructing an installer to connect the new HVAC hardware to apreexisting indoor portion of the split-system HVAC system.

The preexisting indoor portion may include, for example, a preexistingindoor fan motor that is a discrete-speed motor having a first number ofdiscrete non-zero operating speeds. In some embodiments, the firstnumber is no more than two, and in some embodiments, the second numberis greater than the first number, as examples. In a number ofembodiments, such a method may further include acts of instructing theinstaller that they may use a preexisting thermostat configured tocontrol the preexisting discrete-speed HVAC unit, instructing theinstaller that they may reuse preexisting electrical wiring to thepreexisting thermostat, instructing the installer that they may connectthe preexisting electrical wiring to the new controller, or acombination thereof, as examples.

Such instructions (or other instructions for an installer, purchaser, orowner) may be provided, for example, on product packaging, in aninstallation manual or written installation instructions, throughstickers placed on the product, on an Internet website, through aninstructional video, through training courses, or the like, as examples,Such instructions may include text, which may be in one or morelanguages, drawings, pictures, audio, video, or a combination thereof,as examples.

Further, in some embodiments, the act of providing new HVAC hardware mayinclude providing a new outdoor heat exchanger, a new outdoor fanpositioned and configured to move outdoor air through the outdoor heatexchanger, a new outdoor fan motor, a new outdoor portion housing, or acombination thereof, as examples. In some embodiments, the preexistingindoor fan motor may be a single-speed motor having one discretenon-zero operating speed, for example, and the thermostat may beconfigured to control the preexisting HVAC unit by providing an on-offthermostat signal for turning the HVAC unit on or off. In someembodiments, the method includes operating the HVAC unit at more thanone non-zero compressor speed using the on-off thermostat signal fromthe thermostat and selecting the compressor speed based on the timebetween changes in the on-off thermostat signal, for example (orobtaining or providing a controller configured or having instructions todo so).

On the other hand, in some embodiments, the preexisting indoor fan motormay be a two-speed motor having two discrete non-zero operating speeds,and the thermostat may be configured, for example, to control thepreexisting discrete-speed HVAC unit by providing two distinct on-offthermostat signals for turning the HVAC unit on or off and for selectingbetween a high and a low speed. In some embodiments, the method includesoperating the HVAC unit at more than two non-zero compressor speedsusing the on-off thermostat signals from the thermostat and selectingthe compressor speed based on the on-off thermostat signals and the timebetween changes in the on-off thermostat signal, as another example (orobtaining or providing a controller configured or having instructions todo so).

In various embodiments, the new controller may be configured, forexample, so that, when the HVAC unit is operating in a cooling mode, thecontroller selects a higher compressor speed if the outdoor temperatureexceeds a first preset temperature threshold. In addition, or instead,in some embodiments, the new controller may be configured, for example,so that, when the HVAC unit is operating in a heating mode, thecontroller selects a higher compressor speed if the outdoor temperatureis below a second preset temperature threshold. In some embodiments, thenew controller may be configured, for example, to select a lowercompressor speed if a time that the compressor has run is below aminimum time threshold. And in some embodiments, the new controller maybe configured, for example, to select a higher compressor speed if atime that the compressor has run exceeds a maximum time threshold.

In some embodiments, the new controller may be configured, for example,to operate the outdoor fan motor at different outdoor fan speeds atdifferent compressor speeds. Additionally, in a number of embodiments,such a method may further include, for example, an act of providing anoutdoor sensor, for instance, positioned and configured to measure anoutdoor temperature. In some embodiments, the new controller may beconfigured, for example, to receive input from the outdoor sensor and toselect the compressor speed based on (e.g., among other things) theoutdoor temperature. In particular embodiments, the outdoor sensor, forexample, may be positioned and configured to sense outdoor heatexchanger temperature specifically, and the new controller may beconfigured, for instance, to select the compressor speed based on theoutdoor heat exchanger temperature (e.g., once steady state conditionshave been reached).

Yet another example of methods are methods of reducing the cost ofreplacing preexisting HVAC hardware having a first number of discretenon-zero compressor speeds with new HVAC hardware having a greaternumber of compressor speeds. Such methods may include, similar topreviously-described methods, an act of providing new HVAC hardware,which may include, for example, at least a new compressor, a newcompressor motor, a new variable-speed drive for the compressor motor,and a new controller, for example. In some embodiments, the newcontroller may be configured, for example, to operate the newvariable-speed drive at a second number of non-zero compressor speedsusing at least one on-off thermostat signal from a thermostat configuredto control a discrete-speed HVAC unit by providing the on-off thermostatsignal for each discrete speed. In some embodiments, the second numbermay be greater than the first number, for instance. Further, in someembodiments, the new controller may be configured to measure timebetween changes in the on-off thermostat signal, and select thecompressor speed based on the time between changes in the on-offthermostat signal.

In various embodiments, the first number may be one, the first numbermay be two, the second number may be two, the second number may bethree, the second number may be four, the second number may be five, thesecond number may be greater than two, the second number may be greaterthan five, or the second number may be greater than ten, as examples. Insome embodiments, the act of providing new HVAC hardware may furtherinclude providing (e.g., at least) a new outdoor air heat exchanger, anew outdoor air fan positioned and configured to move outdoor airthrough the outdoor air heat exchanger, a new outdoor air fan motor, anda new housing containing the new compressor, the new compressor motor,the new outdoor air heat exchanger, the new outdoor air fan, and the newoutdoor air fan motor, for example (or a subset thereof). In certainembodiments, the act of providing new HVAC hardware may further includeproviding a new variable-speed drive for the new outdoor air fan motor,and in some embodiments, the new controller may be configured, forexample, to operate the new outdoor air fan motor at multiple speeds. Insome embodiments, the act of providing new HVAC hardware may involveproviding a new outdoor portion of a split system HVAC system, forexample.

In particular embodiments, such a method may further include, forexample, an act of instructing the installer that they may reuse apreexisting indoor portion of the split system HVAC system with the newoutdoor portion of a split system HVAC system. On the other hand, insome embodiments, the act of providing new HVAC hardware may furtherinclude providing a new indoor air heat exchanger, a new indoor air fanpositioned and configured to move indoor air through the indoor air heatexchanger, a new indoor air fan motor, and a new housing containing thenew indoor air heat exchanger, the new indoor air fan, and the newindoor air fan motor. Specifically, in some embodiments, the act ofproviding new HVAC hardware may further include providing a packagedHVAC unit. Further, in some embodiments, the act of providing new HVAChardware may further include providing a new multi-speed indoor air fanmotor. In some embodiments, the new controller may be configured, forexample, to operate the new indoor air fan motor at multiple speeds. Andin particular embodiments, the act of providing new HVAC hardware mayfurther include providing a new variable-speed drive for the new indoorair fan motor.

In some embodiments, the preexisting indoor fan motor may be asingle-speed motor having one discrete non-zero operating speed, and thethermostat may be configured, for example, to control the preexistingHVAC hardware by providing an on-off thermostat signal for turning theHVAC hardware on or off. Further, in some embodiments, the methodincludes operating the HVAC hardware at more than one non-zerocompressor speed using the on-off thermostat signal from the thermostatand selecting the compressor speed based on the time between changes inthe on-off thermostat signal, for example. In other embodiments, thepreexisting indoor fan motor may be a two-speed motor having twodiscrete non-zero operating speeds, and the thermostat may beconfigured, for example, to control the preexisting discrete-speed HVAChardware by providing two distinct on-off thermostat signals for turningthe HVAC hardware on or off and for selecting between a high and a lowspeed, as another example.

These on-off thermostat signals may be, for example, 24 volt AC signals,which may be 24 volts to indicate on, and 0 volts to indicate off, forexample. For a single-speed unit (e.g., having a singe-stagethermostat), a pair of wires may have a voltage when the unit is to beon, and may lack voltage when the unit is to be off. For a two-speedunit (e.g., having a two-stage thermostat), there may be three wires.One may be a common wire, one may have voltage when the unit is on, andmay lack voltage when the unit is off, and the third wire may havevoltage when the unit is at high speed and may lack voltage at lowspeed, as an example. In some embodiments, the thermostat may act as aswitch and may provide continuity (i.e., a closed switch) for on or highspeed, and may provide lack of continuity (i.e., an open switch) for offor low speed, as examples. In a number of embodiments, a thermostat(e.g., for a preexisting unit or a discrete-speed unit) may have anadditional wire or pair of wires for signaling whether the blower is tobe on (run all of the time, whether the compressor is running or not) oron auto (run only when the compressor motor is running). Somethermostats may have or use additional wires for additional speeds orfor other functions.

Various methods involve operating the HVAC hardware at more than twonon-zero compressor speeds using the on-off thermostat signals from thethermostat and selecting the compressor speed based on the on-offthermostat signals and the time between changes in the on-off thermostatsignal. Further, a number of embodiments include providing an outdoorsensor positioned and configured to measure an outdoor temperature(e.g., outdoor air heat exchanger). In some embodiments, the newcontroller may be configured, for example, so that, when the HVAChardware is operating in a cooling mode, the controller selects a highercompressor speed if the outdoor temperature exceeds a first presettemperature threshold, or selects a higher compressor speed if theoutdoor temperature is below a second preset temperature threshold, asexamples. In some embodiments, the new controller may be configured, forexample, to select a lower compressor speed if a time that thecompressor has run may be below a minimum time threshold, or to select ahigher compressor speed if a time that the compressor has run exceeds amaximum time threshold, for instance.

Some such methods may further include, for example, an act ofinstructing an installer that they may reuse a preexisting thermostatconfigured to control the preexisting HVAC hardware having the firstnumber of discrete compressor speeds, an act of instructing theinstaller that they may reuse preexisting electrical wiring to thepreexisting thermostat, an act of instructing the installer that theymay connect the preexisting electrical wiring to the new controller, ora combination thereof, as examples. In some embodiments, the act ofproviding new hardware may include providing a controller that may beconfigured, for example, to select the compressor speed utilizing a timebetween a thermostat on signal and a thermostat off signal. In certainembodiments, the controller may be configured, for example, to selectthe compressor speed utilizing a time between a thermostat on signal anda present time. Further, in some embodiments, the act of providing newhardware may include providing a controller that may be configured, forexample, to select the compressor speed utilizing (e.g., among otherthings) a time between a thermostat off signal and a thermostat onsignal.

People, such as an organization or a company, may perform many of themethods described herein. Other methods may be performed by equipmentsuch as a controller (e.g., an HVAC unit controller), or a unit asanother example. Some embodiments include various methods of controllingan air conditioning unit to limit use of electricity while maintainingspace temperature within a desired range, for example. In someembodiments, the air conditioning unit may be a heat pump, for instance,and may be controlled in a heating mode (e.g., as well as in a coolingmode), for example.

Such methods may include, for instance, (e.g., in the following order)at least the acts of receiving an on-signal from a thermostat locatedwithin the space, operating the unit at an operating speed (e.g.,including running a compressor motor driving a compressor at acompressor speed, running an evaporator fan motor at a blower speed, theevaporator fan motor driving an evaporator fan that moves indoor airthrough an evaporator and to the space, and running a condenser fanmotor at a condenser fan speed, the condenser fan motor driving acondenser fan that moves outdoor air through a condenser), and measuringhow long the unit operates. In a number of embodiments, if the unitoperates for longer than a predetermined maximum desired operating time,and if the unit is not already operating at a maximum operating speed,the method may include increasing the operating speed (e.g., increasingthe compressor speed). In various embodiments, the predetermined maximumdesired operating time may be about 21 minutes, about 25 minutes, about30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about50 minutes, about 55 minutes, about 60 minutes, about 70 minutes, orabout 85 minutes, as examples.

Such methods may further include an act of receiving an off-signal fromthe thermostat located within the space, and after receiving theoff-signal, stopping operation of the unit. In various embodiments, theact of stopping operation of the unit may mark an end to an operatingcycle having a final compressor speed at the time the off-signal isreceived. As used herein, an operating cycle, on cycle, or run (e.g.,prior run or immediate prior run) extends from when the thermostatprovides an on-signal until when the thermostat instructs the unit toturn off (e.g., by no longer providing the on-signal). In manyembodiments, the act of stopping operation includes turning off thecompressor motor, turning off the evaporator fan motor, and turning offthe condenser fan motor, as examples. In some embodiments, turning offof one or more of these pieces of equipment may be delayed, for example,for a specific amount of time. For instance, in some embodiments, theevaporator fan or indoor air fan may run for a number of seconds orminutes after the compressor and the condenser fan or outdoor fan turnoff.

Various such methods further include receiving an on-signal from thethermostat (e.g., located within the space), and operating the unit atthe operating speed. In some embodiments, for example, if the compressorspeed was changed during an immediately previous operating cycle, thecompressor speed may be set at the final compressor speed of theimmediately previous operating cycle. As used herein, in evaluatingwhether the compressor speed changed during an immediately previousoperating cycle, starting and stopping of the compressor, and operationof the compressor at a start speed (in embodiments having a startspeed), are not considered. In other words, as used herein, thecompressor speed is only considered to have been changed during theimmediately previous operating cycle, if during the immediately previousoperating cycle, the compressor speed was set (e.g., by the controller)at one steady non-zero compressor speed (other than the start speed) andthen the compressor speed was changed to a different steady non-zerocompressor speed, during the same operating cycle. Further, as usedherein, the final compressor speed of the immediately previous operatingcycle is the non-zero speed at which compressor was operating when thethermostat provided the off signal (e.g., stopped providing an onsignal).

On the other hand, if the compressor speed was not changed during theimmediately previous operating cycle, if the unit operated for less thana predetermined minimum desired operating time during the immediatelyprevious operating cycle, if the unit did not operate at a minimumnon-zero operating speed during the immediately previous operatingcycle, or a combination thereof, an act may be performed of decreasingthe compressor speed from the final compressor speed of the immediatelyprevious operating cycle, for instance. In various embodiments, thepredetermined minimum desired operating time may be, about 12 minutes,about 14 minutes, about 17 minutes, about 20 minutes, about 24 minutes,about 29 minutes, about 35 minutes, about 42 minutes, about 51 minutes,or about 62 minutes, as examples.

Further, in a number of embodiments, if the compressor speed was notchanged during the immediately previous operating cycle, if the unitoperated for more than the predetermined minimum desired operating timeduring the immediately previous operating cycle, if the unit did notoperate at a maximum non-zero operating speed during the immediatelyprevious operating cycle, or a combination thereof, for example, thecompressor speed may be set at the final compressor speed of theimmediately previous operating cycle. Such methods may also includereturning to the act above of measuring how long the unit operates, andrepeating (e.g., indefinitely) that act and the acts that follow (e.g.,until the unit is turned off by the operator).

In some embodiments, available non-zero compressor speeds consist of(i.e., only) a low speed, a high speed, and a boost speed, for example.In variable-speed embodiments, motors may ramp up (e.g., gradually or ata controlled rate) from stop or between speeds, but may operate at aconstant speed (e.g., in steady state) only at the available speeds(e.g., once such available speeds are selected). In some embodimentshaving these available three speeds, the low speed may be the minimumnon-zero speed and the boost speed may be the maximum speed. Thesespeeds may be selected speeds, for example. In a number of embodiments,the unit may be more efficient at the low speed than at the high speed.Further, in many embodiments, the unit may be more efficient at the highspeed than at the boost speed. Moreover, units are generally quieter atlower speeds.

In some embodiments, the blower speed may be constant (i.e., the same)for all (e.g., non-zero) compressor speeds, for example, in applicationswhere a preexisting blower, evaporator fan, or indoor fan is used. Insuch embodiments, if the compressor is operated too slowly (e.g., if lowspeed or the minimum available or selected speed is too low), efficiencymay drop because fan energy (i.e., of the indoor fan at least) does notdecrease as the capacity of the unit decreases. This may limit thenumber of speeds that can be used or how low the speeds can become. Onthe other hand, in some embodiments, for different operating speeds, theblower or indoor fan speed may change as the compressor speed changes.Similarly, in a number of embodiments, for different operating speeds,the condenser fan (i.e., outdoor fan) speed may change as the compressorspeed changes. Embodiments having multiple or variable-speed fans maybenefit from a greater number of available speeds or lower minimumavailable speeds in comparison to units that have single-speed fans, forexample.

In various embodiments, the act of operating the unit at the operatingspeed may include instructing a variable-speed drive to operate thecompressor at one of a discrete number of predetermined speeds. In someembodiments, these predetermined speeds include the maximum compressorspeed and the minimum non-zero compressor speed. In some embodiments,the maximum speed and the minimum non-zero speed are selected at thetime of installation of the unit. On the other hand, in someembodiments, the maximum speed and the minimum non-zero speed may beselected at the factory. Besides the three-speed embodiment describedabove, in other embodiments, available non-zero compressor speeds mayconsist of two discrete non-zero speeds, consist of four discretenon-zero speeds, consist of five discrete non-zero speeds, consist ofsix discrete non-zero speeds, consist of seven discrete non-zero speeds,or may include at least eight discrete non-zero speeds, as otherexamples.

In some embodiments, the air conditioning unit may be a split system,and in some embodiments, at least the compressor motor and thecompressor may have been replaced with a new compressor motor and a newcompressor that are being used with a preexisting evaporator fan motorand a preexisting evaporator fan. In a number of embodiments, the newcompressor motor may be a variable-speed motor driven by avariable-speed drive and the preexisting evaporator fan (i.e., indoorfan or blower) motor may be a single-speed motor. In other embodiments,the evaporator fan motor may be a multiple-speed motor configured tooperate at multiple discrete non-zero blower speeds. For example, incertain embodiments, the evaporator fan motor may be a two-speed motorconfigured to operate at two discrete non-zero blower speeds.

In a number of embodiments, at least the compressor motor and thecompressor have been replaced with a new compressor motor and a newcompressor that are being used with a thermostat configured to control adiscrete-speed HVAC unit by providing an on-off thermostat signal foreach discrete speed. Specifically, in some embodiments, at least thecompressor motor and the compressor have been replaced with a newcompressor motor and a new compressor that are being used with apreexisting thermostat that provides the on-signal and the off-signal.In some embodiments, the thermostat (e.g., new or preexisting) may beelectrically connected to the air conditioning unit through preexistingthermostat wiring.

In particular embodiments, if the compressor speed was not changedduring the immediately previous operating cycle, and if the unitoperated at the maximum non-zero operating speed (e.g., the boost speed)during the immediately previous operating cycle, the method may decreasethe operating speed from the immediately previous operating cycle, forexample (e.g., to the high speed). In some embodiments, the act ofdecreasing the operating speed includes decreasing the compressor speed,for example.

Further, in some embodiments, (e.g., if the unit did not operate at aminimum non-zero operating speed during the immediately previousoperating cycle, if the unit operated for more than the predeterminedminimum desired operating time during the immediately previous operatingcycle, or both) the act of stopping operation of the unit may includedecreasing the compressor speed to a reduced non-zero compressor speedand operating the unit for a third period of time at the reducednon-zero compressor speed. In some such embodiments, if an on-signal hasnot been received from the thermostat located within the space duringthe third period of time, the method may include turning off thecompressor motor after completion of the third period of time.

This may allow the unit to be operated at a higher-efficiency andlower-noise speed for at least part of the time. In embodiments havingthree available speeds (e.g., low, high, and boost), the reduced speedmay be the low speed, for example. In other embodiments, the reducedspeed may be a different speed, which may be selected, for example, toprovide a greater efficiency, reduced noise, or both, but may be lowenough so as to not be able to maintain the set point temperature (e.g.,usually). In some embodiments, such a feature may cause the unit tocycle between a high speed or boost speed and the reduced speed ratherthan cycling between the high speed or boost speed and off, for example.In some embodiments, the reduced speed may only be implemented followingreception of a thermostat off-signal if the unit was operating at theboost speed. In other embodiments, the third period of time may belonger if the unit was operating in the boost speed than if the unit wasoperating at the high speed.

In various embodiments, the third period of time may be, for example,about 12 minutes, about 14 minutes, about 17 minutes, about 20 minutes,about 24 minutes, about 29 minutes, about 35 minutes, about 42 minutes,about 51 minutes, or about 62 minutes, as examples, which may bemeasured from the thermostat off signal, for example. In someembodiments, a provision may be made to allow the user to turn off theunit completely if the unit is operating at the reduced speed. Forexample, in some embodiments, if, when operating at the reduced speedduring the third period of time, the unit receives an on-signal and thenan off-signal (e.g., in quick succession), then the unit may shut offcompletely. As a result, an operator can shut the unit off completely(i.e., without operating at the reduced speed for the third period oftime) by turning the unit off, then on, and then off, in quicksuccession, at the thermostat.

In some embodiments, if the thermostat calls for the unit to operate atthe maximum speed or boost speed for longer than a fourth period oftime, the speed may be reduced (e.g., to the high speed or to the lowspeed) for a fifth period of time. This may spare the compressor,compressor motor, variable-speed drive, or a combination thereof, fromstress and wear associated with continuous operation at the maximumspeed or boost speed for longer than the fourth period of time. In someembodiments, if the thermostat still calls for the unit to operate, theunit may return to the maximum or boost speed after the fifth time. Insome embodiments, the fourth period of time may be about 60 minutes,about 72 minutes, about 86 minutes, about 100 minutes, about 120minutes, about 140 minutes, about 170 minutes, or about 200 minutes, asexamples. Further, in some embodiments, the fifth period of time may beabout 5 minutes, about 6 minutes, about 7 minutes, about 8 minutes,about 9 minutes, about 10 minutes, about 12 minutes, or about 15minutes, as examples.

With some compressors, it may be necessary or beneficial to avoidsustained operation at a low speed in order to assure proper lubricationof the compressor. Some embodiments may provide for an increase inspeed, even if for a short time, to provide such a benefit. Someembodiments provide as a solution to this problem that the compressorspeed automatically increases (e.g., after the predetermined maximumdesired operating time described above). Some embodiments may providefor one or more additional transient increases in speed within thepredetermined maximum desired operating time, (e.g., if operating at alow speed) which may last, for example, about 1 minute, about 2 minutes,about 3 minutes, about 4 minutes, about 5 minutes, about 6 minutes,about 7 minutes, about 8 minutes, about 9 minutes, about 10 minutes, orabout 12 minutes, as examples.

Various methods may further include, for example, an act of measuring atemperature, for instance, at the condenser. For example, in someembodiments, the act of measuring a temperature at the condenser mayinclude measuring a coil temperature. Further, in some embodiments, theact of operating the unit at the operating speed may include (e.g.,among other things) selecting a higher compressor speed if thetemperature exceeds a first threshold temperature, selecting a lowercompressor speed if the temperature is below the first thresholdtemperature, or both (e.g., depending on the temperature). Such acts mayoccur in a cooling mode, for example. In some embodiments, the firstthreshold temperature may be approximately 80 degrees F., approximately89 degrees F., approximately 92 degrees F., approximately 95 degrees F.,or approximately 105 degrees F., as examples.

In some embodiments, the act of operating the unit at the operatingspeed may include selecting a higher compressor speed if the temperatureis below a second threshold temperature, and selecting a lowercompressor speed if the temperature exceeds the second thresholdtemperature. Such acts may occur in a heating mode (e.g., of a heatpump), for example. In certain embodiments, the second thresholdtemperature may be approximately 30 degrees F., approximately 34 degreesF., approximately 37 degrees F., approximately 40 degrees F., orapproximately 50 degrees F., as examples.

In some specific examples of embodiments, when the inverter board ispowered on, the compressor speed (NSP) is set to High. Further, in thisembodiment, when the compressor is turned on for the first time, thecompressor speed is set to High. The speed may change while thecompressor is running or at the next on cycle, for example. Furthermore,in this example, NSP represents the compressor speed at any given momentand can be Boost (highest speed), High, or Low (lowest speed). In anumber of embodiments, for each compressor speed, there is acorresponding condenser fan speed. The inverter controller, in thisembodiment, determines whether or not to change the compressor speedevery tw minutes or when the compressor is turned off by the thermostat.

In a number of embodiments, the inverter controller first measures theoutdoor coil temperature (TC), in this example, and compressor run time(RT). RT is defined, in this embodiment, as the compressor run timewithout speed change. Right after compressor speed changes during runtime, RT is reinitiated (set to zero) in this example.

Further, if the compressor is turned off before tw has passed, andcompressor speed is changed during run time, (but the stage did notchange, in embodiments having multiple stages), in this embodiment, NSPwill not change (within the same stage) when the compressor is turned onagain by the thermostat. On the other hand, if the compressor is turnedoff before tw has passed and compressor speed is not changed during runtime, in this example, the inverter controller selects the nextcompressor speed (NSP) based on the previous speed. In this embodiment,if the previous compressor speed is Boost, NSP is set to High. But ifthe previous compressor speed is High, and run time (RT) is longer thanthh, in this embodiment, NSP is set to Boost. If the previous compressorspeed is High and RT is shorter than thh, on the other hand, then if RTis longer than th and TC is greater than TL, the next compressor speedis not changed in this example. Further, if the previous compressorspeed is High and RT is shorter than thh, then if RT is longer than thand TC is less than TL, the next compressor speed is set to Low in thisembodiment. In addition, if the previous compressor speed is High and RTis shorter than thh, then if RT is shorter than th, the next compressorspeed is set to Low. On the other hand, in this example, if the previouscompressor speed is Low and RT is longer than tl, the next compressorspeed is set to High. In addition, if the previous compressor speed isLow and RT is shorter than tl, then if TC is greater than TH, the nextcompressor speed is set to High. And if the previous compressor speed isLow and RT is shorter than tl, then if TC is less than TH, the nextcompressor speed is not changed (Low).

Moreover, in this embodiment, if tw has passed and the compressor isstill on, the inverter controller selects the next compressor speedbased on the current compressor speed (NSP). If NSP is Boost, thecompressor will not change speed. In addition, if NSP is High and RT isshorter than thh, in this example, the compressor will not change speed.But if NSP is High, and RT is longer than thh, the compressor speed willbe changed to Boost (and RT will be reinitiated). Similarly, if NSP isLow and RT is longer than tl, the compressor speed will be changed toHigh. But if NSP is Low and RT is shorter than tl, then if TC is lessthan TH, the compressor speed will not change (Low). And if NSP is Lowand RT is shorter than tl, then if TC is greater than TH, the compressorspeed will be set to High in this embodiment.

In some embodiments, the compressor speed may be limited by otherfactors as well. For example, when outdoor ambient is above a certaintemperature, the compressor speed may be limited for reliabilityreasons. In those cases, all the compressor speeds (Boost, High or Low)may be checked against the speed limit. If an intended compressor speedis higher than the speed limit, the speed (e.g., NPS) may be set tomatch the speed limit, in such embodiments. In some embodiments,parameter values and ranges may be as follows: TL=89° F. (±5° F.);TH=95° F. (±5° F.); tl=90 minutes (±30 minutes); th=45 minutes (±30minutes); thh=60 minutes (±30 minutes); tw=10 minutes (±10 minutes), asexamples.

In some embodiments, when the inverter board is powered on, thecompressor speed (NSP) is set to High. Further, when the compressor isturned on for the first time, the compressor speed is High. Inparticular embodiments, the speed may change while the compressor isrunning or at the next on cycle. Further, in some embodiments, NSPrepresents compressor speed at any given moment and can be Boost(highest speed), High, or Low (lowest speed), but these compressorspeeds may be different from the cooling speeds. For each compressorspeed, there may be a corresponding condenser fan speed, in a number ofembodiments. The inverter controller may determine whether or not tochange the compressor speed every tw minutes or when the compressor isturned off by the thermostat, in this embodiment. The invertercontroller may first measure the outdoor coil temperature (TC) andcompressor run time (RT). RT may be defined as the compressor run timewithout speed change, for example. Right after compressor speed changesduring run time, for example, RT may be reinitiated (set to zero) insome embodiments.

In a number of embodiments, if the compressor is turned off before twhas passed and compressor speed is changed during run time, NSP will notchange when the compressor is turned on again by the thermostat.Further, if the compressor is turned off before tw has passed andcompressor speed is not changed during run time, the inverter controllermay select the next compressor speed (NSP) based on the previous speed.If the previous compressor speed was Boost, for example, NSP is set toHigh. On the other hand, if the previous compressor speed is High, andrun time (RT) is longer than thh, NSP is set to Boost. Further, if theprevious compressor speed is High and RT is shorter than thh, then if RTis longer than th and TC is less than TL, the next compressor speed isnot changed (High). Further, if the previous compressor speed is Highand RT is shorter than thh, then if RT is longer than th and TC isgreater than TL, however, the next compressor speed is set to Low. Inaddition, if the previous compressor speed is High and RT is shorterthan thh, then if RT is shorter than th, the next compressor speed isset to Low. But if the previous compressor speed is Low and RT is longerthan tl, the next compressor speed is set to High. But if the previouscompressor speed is Low and RT is shorter than tl, then if TC is lessthan TH, the next compressor speed is set to High. Further, if theprevious compressor speed is Low and RT is shorter than tl, then if TCis greater than TH, the next compressor speed is not changed (Low).

If tw has passed and the compressor is still on, in this embodiment, theinverter controller selects the next compressor speed based on thecurrent compressor speed (NSP). If NSP is Boost, the compressor will notchange speed. In addition, if NSP is High and RT is shorter than thh,the compressor will not change speed. But if NSP is High, and RT islonger than thh, the compressor speed will be changed to Boost (and RTwill be reinitiated). On the other hand, if NSP is Low and RT is longerthan tl, the compressor speed will be changed to High. And if NSP is Lowand RT is shorter than tl, then if TC is greater than TH, the compressorspeed will not change (Low). However, if NSP is Low and RT is shorterthan tl, then if TC is less than TH, the compressor speed will be set toHigh. In this example of an embodiment, parameter values and ranges maybe as follows: TL=40° F. (±5° F.); TH=34° F. (±5° F.); tl=90 minutes(±30 minutes); th=45 minutes (±30 minutes); thh=60 minutes (±30minutes); tw=10 minutes (±10 minutes), as examples.

In a number of embodiments, a stage two cooling algorithm may be thesame, or similar to, a single stage cooling algorithm. As used herein,the number of “stages” (e.g., one or two) refers to the number of speedsignals (not including off) that the thermostat provides, as opposed tothe number of different non-zero speeds that the compressor is actuallyoperated at under different circumstances in the particular embodimentbeing described. In some embodiments, when the inverter board is poweredon, the compressor speed (NSP) may be set to H high. When the thermostatcalls for stage two cooling, the compressor speed is H high. The speedmay change while the compressor is running or at the next on cycle. NSPrepresents compressor speed at any given moment and can be Boost(highest speed), H high, or H low (lowest speed). In a number ofembodiments, for each compressor speed, there may be a correspondingcondenser fan speed. In some embodiments, the inverter controllerdetermines whether or not to change the compressor speed every twminutes or when the compressor is turned off by the thermostat. Theinverter controller may first measure the outdoor coil temperature (TC)and compressor run time (RT). Again, RT is defined as the compressor runtime without speed change. Right after compressor speed changes duringrun time, RT is reinitiated (set to zero) in this embodiment.

Moreover, if the compressor is turned off before tw has passed andcompressor speed is changed during run time, in this embodiment, NSPwill not change when the compressor is turned on again by thethermostat. If the compressor is turned off before tw has passed andcompressor speed is not changed during run time, however, the invertercontroller selects the next compressor speed (NSP) based on the previousspeed. If the previous compressor speed is Boost, NSP is set to H high.On the other hand, if the previous compressor speed is H high, and runtime (RT) is longer than Hthh, NSP is set to Boost. Further, if theprevious compressor speed is H high and RT is shorter than Hthh, then ifRT is longer than Hth and TC is greater than HTL, the next compressorspeed is not changed. Moreover, in this embodiment, if the previouscompressor speed is H high and RT is shorter than Hthh, then if RT islonger than Hth and TC is less than HTL, the next compressor speed isset to H low. In addition, if the previous compressor speed is High andRT is shorter than Hthh, then if RT is shorter than Hth, the nextcompressor speed is set to H low. But if the previous compressor speedis H low and RT is longer than Htl, the next compressor speed is set toH high. In addition, if the previous compressor speed is H low and RT isshorter than Htl, then if TC is greater than HTH, the next compressorspeed is set to H high. But if the previous compressor speed is H lowand RT is shorter than Htl, then if TC is less than HTH, the nextcompressor speed is not changed (H low).

Additionally, in this embodiment, if tw has passed and the compressor isstill on, the inverter controller selects the next compressor speedbased on the current compressor speed (NSP). If NSP is Boost, thecompressor will not change speed. In addition, if NSP is H high and RTis shorter than Hthh, the compressor will not change speed. Further, ifNSP is H high, and RT is longer than Hthh, the compressor speed will bechanged to Boost (and RT will be reinitiated). If NSP is H low and RT islonger than Htl, however, the compressor speed will be changed to Hhigh. On the other hand, if NSP is H low and RT is shorter than Htl,then if TC is less than HTH, the compressor speed will not change (Hlow). But if NSP is H low and RT is shorter than Htl, then if TC isgreater than HTH, the compressor speed will be set to H high.

Again, in a number of embodiments, the compressor speed may be limitedby other factors as well. For example, when outdoor ambient is abovecertain temperature, the compressor speed may be limited for reliabilityreasons. In those cases, all the compressor speeds (Boost, H high or Hlow) may be checked against the speed limit. If any compressor speed ishigher than the speed limit, it may be set to match the speed limitinstead. In certain embodiments, parameter values and ranges may be asfollows: HTL=89° F. (±5° F.); HTH=95° F. (±5° F.); Htl=90 minutes (±30minutes); Hth=45 minutes (±30 minutes); Hthh=60 minutes (±30 minutes);tw=10 minutes (±10 minutes), as examples.

In stage one cooling (e.g., low speeds), the stage one cooling algorithmmay be similar to the stage two cooling algorithm, for example, exceptthat, in some embodiments, the stage one cooling does not have a Boostspeed. In this embodiment, when the thermostat calls for stage onecooling, the compressor speed may start at L high (e.g., ramp steadilyup to L high). The speed may change, however, while the compressor isrunning or at the next on cycle. NSP represents compressor speed at anygiven moment and can be L high, or L low, for example. In someembodiments, for each compressor speed, there is a correspondingcondenser fan speed. The inverter controller may determine whether ornot to change the compressor speed every tw minutes or when thecompressor is turned off by the thermostat, for example. In thisembodiment, the inverter controller first measures the outdoor coiltemperature (TC) and compressor run time (RT). Further, in thisembodiment, RT is defined as the compressor run time without speedchange. Right after compressor speed changes during run time, RT is bereinitiated (set to zero) in this embodiment.

In this embodiment, if the compressor is turned off before tw has passedand compressor speed is changed during run time, NSP will not change (Lhigh) when the compressor is turned on again by the thermostat. If thecompressor is turned off before tw has passed and compressor speed isnot changed during run time, however, the inverter controller selectsthe next compressor speed (NSP) based on the previous speed. If theprevious compressor speed is L high, RT is longer than Lth, and TC isgreater than LTL, the next compressor speed is not changed. But if theprevious compressor speed is L high, RT is longer than Lth, and TC isless than LTL, the next compressor speed is set to L low. In addition,if the previous compressor speed is L high and RT is shorter than Lth,the next compressor speed is set to L low. But if the previouscompressor speed is L low and RT is longer than Ltl, the next compressorspeed is set to L high. In addition, if the previous compressor speed isL low and RT is shorter than Ltl, then if TC is greater than LTH, thenext compressor speed is set to L high. But if the previous compressorspeed is L low and RT is shorter than Ltl, then if TC is less than LTH,the next compressor speed is not changed (L low) in this embodiment.

Furthermore, if tw has passed and the compressor is still on, theinverter controller selects the next compressor speed based on thecurrent compressor speed (NSP). If NSP is L high, the compressor willnot change speed. But if NSP is L low and RT is longer than Ltl, thecompressor speed will be changed to L high. If NSP is L low and RT isshorter than Ltl, then if TC is less than LTH, the compressor speed willnot change (L low). But if NSP is Low and RT is shorter than Ltl, thenif TC is greater than LTH, the compressor speed will be set to L high.

In some embodiments, the compressor speed may be limited by otherfactors as well. For example, when outdoor ambient is above certaintemperature, the compressor speed may be limited by reliability reasons.In those cases, all the compressor speeds (L high or L low) may bechecked against the speed limit, for example. If any compressor speed ishigher than the speed limit, it may be set to match the speed limit. Inparticular embodiments, parameter values and ranges may be as follows:LTL=77° F. (±5° F.); HTH=83° F. (±5° F.); Htl=90 minutes (±30 minutes);Hth=45 minutes (±30 minutes); tw=10 minutes (±10 minutes), as examples.

In stage two heating (e.g., high speeds), the stage two heatingalgorithm may be the same as the single stage heating algorithm, forexample. When the inverter board is powered on, in this embodiment, thecompressor speed (NSP) may be set to High. When the thermostat calls forstage two heating, the compressor speed may initially be set to High.The speed may change, however, while the compressor is running or at thenext on cycle. Again, NSP represent compressor speed at any given momentand can be Boost (highest speed), High, or Low (lowest speed). Thesecompressor speeds may be different from the cooling speeds, in someembodiments. Further, for each compressor speed, there is acorresponding condenser fan speed, in some embodiments. Similar to otherstages, the inverter controller may determine whether or not to changethe compressor speed every tw minutes or when the compressor is turnedoff by the thermostat. The inverter controller may first measure theoutdoor coil temperature (TC) and compressor run time (RT). In thisembodiment, RT is also defined as the compressor run time without speedchange. Right after compressor speed changes during run time, RT isreinitiated (set to zero) in this embodiment.

If the compressor is turned off before tw has passed and compressorspeed is changed during run time, in this embodiment, NSP will notchange when the compressor is turned on again by the thermostat. But ifthe compressor is turned off before tw has passed and compressor speedis not changed during run time, the inverter controller selects the nextcompressor speed (NSP) based on the previous speed. If the previouscompressor speed is Boost, NSP is set to High. But if the previouscompressor speed is High, and run time (RT) is longer than Hthh, NSP isset to Boost. Moreover, if the previous compressor speed is High and RTis shorter than Hthh, then if RT is longer than Hth and TC is less thanHTL, the next compressor speed is not changed (High) in this embodiment.But if the previous compressor speed is High and RT is shorter thanHthh, then if RT is longer than Hth and TC is greater than HTL, the nextcompressor speed is set to Low. In addition, if the previous compressorspeed is High and RT is shorter than Hthh, then if RT is shorter thanHth, the next compressor speed is set to Low. On the other hand, if theprevious compressor speed is Low and RT is longer than Htl, the nextcompressor speed is set to High. If the previous compressor speed is Lowand RT is shorter than Htl, then if TC is less than HTH, the nextcompressor speed is set to High. But if the previous compressor speed isLow and RT is shorter than Htl, then if TC is greater than HTH, the nextcompressor speed is not changed (Low).

In a number of embodiments, if tw has passed and the compressor is stillon, the inverter controller may select the next compressor speed basedon the current compressor speed (NSP), for example. If NSP is Boost, thecompressor will not change speed. In addition, if NSP is High and RT isshorter than Hthh, the compressor will not change speed. But if NSP isHigh, and RT is longer than Hthh, the compressor speed will be changedto Boost (and RT will be reinitiated) in this embodiment. On the otherhand, if NSP is Low and RT is longer than Htl, the compressor speed willbe changed to High. And if NSP is Low and RT is shorter than Htl, thenif TC is greater than HTH, the compressor speed will not change (Low).But if NSP is Low and RT is shorter than Htl, then if TC is less thanHTH, the compressor speed will be set to High. In particularembodiments, parameter values and ranges may be as follows: HTL=40° F.(±5° F.); HTH=34° F. (±5° F.); Htl=90 minutes (±30 minutes); Hth=45minutes (±30 minutes); Hthh=60 minutes (±30 minutes); tw=10 minutes (±10minutes), as examples.

In stage one heating (e.g., low speeds) the algorithm may be similar tothe stage two heating algorithm, for example, except that the stage oneheating may not have a Boost speed. When the thermostat calls for stageone heating, the compressor speed may be set to L high. The speed maychange, however, while the compressor is running or at the next oncycle. NSP represents the compressor speed at any given moment and canbe L high, or L low in this embodiment. These compressor speeds may bedifferent from the cooling speeds, in some embodiments, and for eachcompressor speed, there may be a corresponding condenser fan speed. Theinverter controller may determine whether or not to change thecompressor speed every tw minutes or when the compressor is turned offby the thermostat. The inverter controller may first measure the outdoorcoil temperature (TC) and compressor run time (RT). In this embodiment,RT is defined as the compressor run time without speed change. Rightafter compressor speed changes during run time, RT will be reinitiated(set to zero) in this embodiment.

If the compressor is turned off before tw has passed and compressorspeed is changed during run time, NSP may not change (L high) when thecompressor is turned on again by the thermostat. On the other hand, ifthe compressor is turned off before tw has passed and compressor speedis not changed during run time, the inverter controller may select thenext compressor speed (NSP) based on the previous speed. If the previouscompressor speed is L high, RT is longer than Lth, and TC is less thanLTL, the next compressor speed is not changed (L high). But if theprevious compressor speed is L high, RT is longer than Lth, and TC isgreater than LTL, the next compressor speed is set to L low. Inaddition, if the previous compressor speed is L high and RT is shorterthan Lth, the next compressor speed is set to L low. However, if theprevious compressor speed is L low and RT is longer than Ltl, the nextcompressor speed is set to L high. Additionally, if the previouscompressor speed is L low and RT is shorter than Ltl, then if TC is lessthan LTH, the next compressor speed is set to L high. But if theprevious compressor speed is L low and RT is shorter than Ltl, then ifTC is greater than LTH, the next compressor speed is not changed (Llow).

In various embodiments, if tw has passed and the compressor is still on,the inverter controller selects the next compressor speed based on thecurrent compressor speed (NSP). If NSP is L high, for example, thecompressor will not change speed. But if NSP is L low and RT is longerthan Ltl, the compressor speed will be changed to L high. And if NSP isL low and RT is shorter than Ltl, then if TC is greater than LTH, thecompressor speed will not change (L low). But if NSP is L low and RT isshorter than Ltl, then if TC is less than LTH, the compressor speed willbe set to L high. In particular embodiments, parameter values and rangesmay be as follows: HTL=50° F. (±5° F.); HTH=44° F. (±5° F.); Htl=90minutes (±30 minutes); Hth=45 minutes (±30 minutes); tw=10 minutes (±10minutes), as examples.

Yet other examples of methods include various methods of adapting anddistributing heat pumps, for example, to provide improved efficiencyperformance in different climates where demand for cooling and heatingare substantially unequal. In various embodiments, such methods mayinclude (e.g., in any order) at least the acts of obtaining ormanufacturing an inventory of heat pumps having (at least) substantiallyidentical compressors, compressor motors, variable-speed drives for thecompressor motors, outdoor heat exchangers, outdoor fans, outdoor fanmotors, and variable-speed drives for the outdoor fan motors, andobtaining or providing substantially identical controllers for each ofthe heat pumps, each controller including, for example, instructions tooperate the compressor motor at multiple different speeds in each of acooling mode and a heating mode. As used herein, “substantiallyidentical” means similar enough in dimensions and performance so as tobe interchangeable in mass production.

In a number of embodiments, such methods may also include dividing theinventory of heat pumps in to multiple groups of multiple heat pumps,and assigning different ratings to each group of heat pumps. Thedifferent ratings (i.e., between groups) may differ in capacity in atleast one of the cooling mode or the heating mode, and in someembodiments, for at least one of the groups, a rating in the coolingmode may be substantially different than a rating in the heating mode,for example. Further, such methods may include an act of configuring(e.g., programming or inputting selections) the controllers of eachgroup of heat pumps to operate the compressor motors of the heat pumpsin that group at selected speeds that provide performance thatcorresponds to the rating of the group (e.g., in both cooling andheating modes).

In many embodiments, for at least one of the groups, a selected speed ofthe compressor motor in the cooling mode may be substantially differentthan any selected speed of the compressor motor (e.g., of the same unit)in the heating mode, for example. In some embodiments, for at least oneof the groups, all selected speeds of the compressor motor in thecooling mode or all selected speeds of the compressor motor in theheating mode may be substantially below a maximum capable compressormotor speed for the heat pump, as examples. In some embodiments, atleast one selected speed of the compressor motor that may besubstantially below a maximum capable compressor motor speed for theheat pump provides a higher efficiency of the heat pump than the maximumcapable compressor motor speed, for instance.

Various embodiments further include acts of advertising the differentratings of each group of heat pumps. Such advertising may include, forexample, advertising the higher efficiency, for example. Advertising maybe performed, for example, through the media (e.g., television orradio), over the Internet (e.g., Internet advertisements, e-mails, orone or more web sites), through flyers, on product packaging, ondisplays where products are sold, through the mail, using salesrepresentatives, through telephone calls, by text messaging, at tradeshows, or the like, as examples. Advertising may be made todistributors, dealers, installation contractors, or directly to thepubic, building owners, or building managers. A number of embodimentsmay further include selling the heat pumps in the different groups foruse in different applications (e.g., for buildings located in differentlocations having different climates) having different unequal demandsfor heating and cooling. Sales may be made, for example, todistributors, dealers, installation contractors, or directly to thepubic, building owners, or building managers, for instance. In someembodiments, heat pumps may be priced differently depending on theratings (e.g., higher rated units may be sold at higher prices thanlower rated units, even though the only differences lie in the controls.In some situations, lower rated units may have greater efficiencies, andtherefore, may qualify for incentives that higher rated units do notqualify for. In a number of embodiments, such incentives may beadvertised.

In certain embodiments, units may be derated (e.g., the selected speedsbeing below or substantially below the maximum capable compressor motorspeed) in both the cooling and heating modes. Units that are derated inboth the cooling and heating modes may be more efficient, may provideone or more capacities without designing, building, and inventoryingdifferent size units or components, may last longer, may be suitable formore severe ambient conditions (e.g., higher summer temperatureclimates), or a combination thereof, as examples (e.g., in comparisonwith units that operate at the maximum capable compressor motor speed).In some embodiments, deratings and the speed changes associatedtherewith may be made in the factory, and may be difficult to change inthe field (e.g., physically difficult or may require information thatmay be kept secret such as codes, software, or know how). Derated unitsmay be sold at different prices (e.g., lower prices) than full ratedunits, may qualify for incentives due to their higher efficiency, mayhave different warranties, may have lower noise ratings, or acombination thereof, as examples, which may be advertised. In otherembodiments, deratings may be easier to make and may be made by theinstaller or even by the owner (e.g., home owner).

In some embodiments, the act of configuring the controllers may beperformed for each heat pump before the heat pump is shipped to aninstallation site or before the heat pump may be installed, such as in afactory where the heat pump may be assembled, for example. In someembodiments, the heat pump may be an outdoor portion of a split systemHVAC system. On the other hand, in some embodiments, the heat pump maybe a packaged HVAC unit or a complete split system (e.g., both outdoorand indoor portions). In certain embodiments, the act of obtaining ormanufacturing the inventory of heat pumps may include obtaining ormanufacturing an inventory of heat pumps having, at least, (e.g., inaddition to other components) substantially identical indoor heatexchangers, indoor fans, indoor fan motors, variable-speed drives forthe indoor fan motors, or a combination thereof, as examples.

In various embodiments, the act of obtaining or providing substantiallyidentical controllers for each of the heat pumps may include obtainingor providing controllers that are each configured to operate thecompressor motor at a first number of different selected speeds in thecooling mode and a second number of different selected speeds in theheating mode. In some embodiments, the first number and the secondnumber are both whole numbers, and in some embodiments, the act ofconfiguring the controllers of each group of heat pumps may includeproportionally lowering multiple, some, all except for one, or all, ofthe first number of different selected speeds in the cooling mode, forexample.

In some embodiments, the lowest speed may remain unchanged, and theother speeds may be reduced proportionally (e.g., from the maximumcapable compressor motor speed for the heat pump) for instance. Inaddition, or instead, in some embodiments, the act of configuring thecontrollers of each group of heat pumps may include proportionallylowering multiple, some, all except for one (e.g., all except for thelowest speed), or all, of the second number of different selected speedsin the heating mode, for instance.

In some embodiments, the first number may be equal to the second number,while in other embodiments, the first number may not be equal to thesecond number. In particular embodiments, the first number may begreater than two, the first number may be less than ten, the secondnumber may be greater than two, the second number may be less than ten,or a combination thereof, as examples. Further, in certain embodiments,the act of configuring the controllers of each group of heat pumps mayinclude lowering multiple (e.g., some, all except for one, or all)selected speeds in the cooling mode proportionally to a reduction ofrated capacity in the cooling mode or lowering multiple (e.g., some, allexcept for one, or all) selected speeds in the heating modeproportionally to a reduction of rated capacity in the heating mode (orboth, in some embodiments).

Further, in some embodiments, the act of configuring the controllers ofeach group of heat pumps may include configuring the controllers tooperate the outdoor fan motors of the heat pumps at different speeds fordifferent compressor speeds, configuring each of the controllers tooperate the outdoor fan motor of the heat pump at a speed that may beproportional to a concurrent compressor speed, or both, as examples.Similarly, in some embodiments, the act of configuring the controllersof each group of heat pumps may include configuring the controllers tooperate indoor fan motors of the heat pumps at different speeds fordifferent compressor speeds configuring each of the controllers tooperate the indoor fan motor of the heat pump at a speed that may beproportional to a concurrent compressor speed, or both, as furtherexamples.

Moreover, in some embodiments, the act of selecting the compressor speedbased on the time between changes in the on-off thermostat signal mayinclude utilizing a time between a thermostat on signal and a thermostatoff signal. In addition, or instead, in particular embodiments, the actof selecting the compressor speed based on the time between changes inthe on-off thermostat signal may include utilizing a time between athermostat on signal and a present time. Further, in some embodiments,the act of selecting the compressor speed based on the time betweenchanges in the on-off thermostat signal may include utilizing a timebetween a thermostat off signal and a thermostat on signal.

Other examples of methods includes some or all of the following acts:

1. Test a variable speed system (compressor, fan motor, blower motor) atdifferent speeds and ambient conditions.

2. Measure its capacities and energy efficiency.

3. Determine a speed set SPH (e.g., compressor, fan motor, blower motorspeeds) at which the heat pump provide its highest cooling and heatingcapacities. The cooling compressor speed set=CoolH1 (lowest speed),CoolH2, . . . . CoolHN (highest speed). The heating compressor speedset=HeatH1 (lowest speed), HeatH2, . . . HeatHN (highest speed). Theindoor blower and outdoor fan motors have the similar speed sets.

4. Determine another speed set SPL (compressor, fan motor, blower motorspeeds) at which the heat pump provide its lowest cooling and heatingcapacities. The cooling compressor speed set=CoolL1 (lowest speed),CoolL2, . . . . CoolLN (highest speed). The heating compressor speedset=HeatL1 (lowest speed), HeatL2, . . . HeatLN (highest speed). Theindoor blower and outdoor fan motors have the similar speed sets.

5. Determine a ratio “Rc” (Cooling) and Rh (heating) between 0 and 1.

6. Calculate new speeds NS for the heat pump rated at a differentcooling and heating capacities whereCoolNS1=Rc*CoolL1+(1−Rc)*CoolH1 . . .CoolNSN=Rc*CoolLN+(1−Rc)*CoolHN.  a.HeatNS1=Rh*HeatL1+(1−Rh)*HeatH1 . . .HeatNSN=Rh*HeatLN+(1−Rh)*HeatHN.  b.

7. Use the same method to calculate the cooling and heating outdoor fanspeed sets using Rc and Rh.

8. Use the same method to calculate the cooling and heating indoorblower speed sets using Rc and Rh.

9. Test the heat pump with the new speed sets.

10. Evaluate the new cooling, heating capacities, and energy efficiency.

11. Repeat 5 to 10 with different Rc and Rh.

12. Create a cooling and heating table.

13. Store the high and low speed sets (SPH and SPL) in the controllermemory.

14. Reserve memory space for Rc set and Rh set.

15. If a set of Rc and Rh is selected, the compressor speed can bedetermined as follows:CoolNS1=Rc*Cool L1+(1−Rc)*CoolH1 . . . .CoolNSN=Rc*CoolLN+(1−Rc)*CoolHN.  a.HeatNS1=Rh*HeatL1+(1−Rh)*HeatH1 . . .HeatNSN=Rh*HeatLN+(1−Rh)*HeatHN.  b.

16 Use the same method to calculate the cooling and heating outdoor fanspeed sets using Rc and Rh.

17 Use the same method to calculate the cooling and heating indoorblower speed sets using Rc and Rh.

18 Program the controller in the factory to allow the same heat pumphardware to be rated at different cooling and heating capacitycombinations.

19. Alternatively, allow the installer to select different cooling andheating capacities in the field by using dipswitches, jumpers, keypad,or equivalent means.

Turning now to the figures, and the particular embodiments illustratedtherein, FIG. 1 illustrates an example of a method, method 10, ofcontrolling an HVAC unit, which may be an air conditioning unit or aheat pump operating in a cooling mode, for example, using a signal froma single-speed or single-stage thermostat. In this embodiment, the HVACunit has a compressor, and the HVAC unit is configured to operate thecompressor at multiple compressor speeds. Specifically, the multiplecompressor speeds include a low speed, a high speed, and a boost speed,in this embodiment, and the HVAC unit (e.g., the controller thereof) isconfigured to operate the compressor using a signal from a single-speedor single-stage thermostat and to select a current compressor speed fromthe multiple compressor speeds.

In this embodiment, method 10 includes, for example, when a current runsignal is received from the thermostat (e.g., detected in act 101), anact of starting the compressor (e.g., act 103). As used herein, certainacts are described as conditional, for example, “when” a condition ispresent, or “if” a condition exists. Such language means and requiresthat the existence of the condition stated be evaluated, and that thedescribed action is taken if the condition exists. Further, as usedherein, “when” means while the condition exists, but does not requirethat the action necessarily be taken instantaneously.

In the embodiment illustrated, method 10 also includes an act ofevaluating whether the compressor speed changed during an immediateprior run (e.g., act 115). In a number of embodiments, the immediateprior run may have had a prior run final compressor speed and a priorrun time, for example, which may have been measured (e.g., in act 106),and stored (e.g., in computer memory). In this embodiment, if thecompressor speed changed during the immediate prior run (e.g., evaluatedin act 115), method 10 includes an act of operating the compressor atthe prior run final compressor speed (e.g., act 122) during the currentrun signal (e.g., act 104). In other words, the unit is operated, atleast initially, at the same speed as at the end of the prior run, ifthe speed changed during the prior run.

Further, if the compressor speed did not change during the immediateprior run (e.g., evaluated in act 115), method 10 includes an act ofevaluating whether the prior run final compressor speed was the boostspeed (e.g., in act 116), and if the prior run final compressor speedwas the boost speed, method 10 includes operating the compressor at thehigh speed (e.g., act 123 and 104) during the current run signal. (Forexample, the change in speed is made in act 123, and the unit isoperated at that speed in act 104.)

Still further, if the compressor speed did not change during theimmediate prior run (e.g., evaluated in act 115), method 10 includes anact of evaluating whether the prior run final compressor speed (NSP) wasthe high speed (e.g., act 116). If the prior run final compressor speedwas the high speed, method 10 includes evaluating whether the prior runtime (RT) was less than a predetermined high speed minimum desiredoperating time (e.g., th in act 118), and if the prior run time was lessthan the predetermined high speed minimum desired operating time (e.g.,evaluated in act 118), method 10 includes an act of operating thecompressor at the low speed (e.g., act 125 and 104) during the currentrun signal.

Moreover, if the compressor speed did not change during the immediateprior run (e.g., evaluated in act 115), if the prior run finalcompressor speed was the high speed (e.g., evaluated in act 116), and ifthe immediate prior run time was more than the predetermined high speedminimum desired operating time (e.g., evaluated in act 118), method 10includes an act of operating the compressor at the high speed (e.g., act123 and 104) during the current run signal. Thus, under theseconditions, high speed operation is repeated, at least initially.

Method 10 further includes an act of measuring a current speed operatingtime during the current run signal (e.g., act 106), and if the currentcompressor speed is the low speed (e.g., evaluated in act 108) and ifthe current speed operating time is greater than a predetermined lowspeed maximum desired operating time (e.g., evaluated in act 111),method 10 includes increasing the compressor speed to the high speed(e.g., act 113) during the current run signal. Unless stated otherwise,as used herein the “current speed operating time” is the time at oneconstant speed (e.g., low, high, or boost). Still further, method 10includes an act of measuring the current speed operating time during thecurrent run signal (e.g., act 106), and if the current compressor speedis the high speed (e.g., evaluated in act 108) and if the current speedoperating time is greater than a predetermined high speed maximumdesired operating time (e.g., evaluated in act 109), increasing thecompressor speed to the boost speed (e.g., in act 110) during thecurrent run signal. In the embodiment illustrated, method 10 alsoincludes, after the current run signal is no longer received from thethermostat (e.g., 105), stopping the compressor (e.g., act 107) andrepeating the above acts (e.g., starting with act 101) when the runsignal (e.g., from the single-stage thermostat) is restored.

Method 10, in the embodiment illustrated, also includes, when thecurrent run signal is first received from the thermostat (e.g.,evaluated in act 102), an act of starting the compressor, ramping thecompressor up to a start speed, and operating the compressor for apredetermined desired start time at the start speed (e.g., act 114).This may be beneficial for the compressor, the variable-speed drive, orboth, and may make the starting of the unit less obtrusive to people(e.g., in the building). In a number of embodiments, the start speed issubstantially the same regardless of the prior run final compressorspeed (e.g., NSP evaluated in act 116). Additionally, in a number ofembodiments, the start speed (e.g., of act 114) is within a rangeextending from the low speed to the high speed, inclusive. In particularembodiments, the start speed (e.g., of act 114) may be the low speed,for instance. In other embodiments, the start speed may be a differentspeed, however.

The appropriate acts of method 10 may be repeated or cycled through atregular intervals of time, for example (e.g., tw in act 105). Such aninterval may be (e.g., tw) every two (2) minutes, for example. Further,in some embodiments, when the current run signal is first received fromthe thermostat (e.g., act 101), the method (e.g., 10) includes an act ofevaluating whether the current run signal resulted from a user turningthe HVAC unit on at the thermostat (e.g., act 102). In particularembodiments, if the current run signal resulted from a user turning theHVAC unit on at the thermostat (e.g., determined in act 102), the methodincludes operating the compressor during the current run signal at thehigh speed (e.g., act 103, 104, or both). In some embodiments, thisspeed may be selected regardless of the prior run final compressor speed(e.g., evaluated in act 116). This may make the unit seem moreresponsive to the user, and may result in the temperature within thespace responding more quickly when the user changes the thermostat(e.g., compared to if the unit operated at the low speed until act 109changed the speed).

In the embodiment illustrated, if the compressor speed did not changeduring the immediate prior run (e.g., evaluated in act 116), method 10includes an act of evaluating whether the prior run final compressorspeed was the high speed (e.g., in act 116), and if the prior run finalcompressor speed was the high speed (e.g., evaluated in act 116),evaluating whether an outdoor temperature parameter is beyond a firstthreshold (e.g., act 119). In this embodiment, if the outdoortemperature parameter is beyond the first threshold (e.g., below 100degrees F., as evaluated in act 119), method 10 includes operating thecompressor at the low speed (e.g., act 125 and 104) during the currentrun signal. Further, in this embodiment, method 10, includes an act ofevaluating whether an outdoor temperature parameter is beyond a secondthreshold (e.g., act 112), and if the current compressor speed is thelow speed (e.g., evaluated in act 108), if the outdoor temperature isbeyond the second threshold (e.g., above 105 degrees F., as evaluated inact 112), method 10 includes an act of increasing the compressor speedto the high speed (e.g., act 113) during the current run signal.

In this embodiment, the outdoor temperature parameter may be thetemperature of the outdoor coil (e.g., the condenser coil), for example.Further, the first threshold (e.g., TL) may be 100 degrees F., and thesecond threshold (e.g., TH) may be 105 degrees, F, as examples. In otherembodiments, the outdoor temperature parameter may be outside airtemperature, or a pressure dependent on the outdoor temperature, such ascondenser pressure, as examples. Still further, some embodiments mayinclude an act of varying the boost speed as a function of an outdoortemperature parameter. For example, in a cooling mode, it may bepossible to run at a higher boost speed, without overstressingequipment, if the outdoor air temperature, or specifically, if thecondenser coil temperature, is lower.

Further, in method 10, if the compressor speed did not change during theimmediate prior run (e.g., evaluated in act 115), and if the prior runfinal compressor speed was the boost speed (e.g., evaluated in act 116),the act of operating the compressor during the current run signal at thehigh speed (e.g., act 123 and 104) may be performed regardless of anoutdoor temperature parameter (e.g., TC). Even further, in someembodiments, including in method 10, if the compressor speed did notchange during the immediate prior run (e.g., evaluated in act 115), andif the prior run final compressor speed was the boost speed (e.g.,evaluated in act 116), the act of operating the compressor during thecurrent run signal at the high speed (e.g., act 123 and 104) isperformed regardless of the prior run time (e.g., RT).

In various embodiments, the HVAC unit has a variable-speed drive for thecompressor, but the HVAC unit operates the compressor at only a limitedwhole number of steady compressor speeds. These steady compressor speedsmay include the low speed and the high speed, for example. Further, in anumber of embodiments, the high speed is higher than the low speed andthe boost speed is higher than the high speed. In certain embodiments,the predetermined high speed minimum desired operating time (e.g., thused in act 118) may be less than the predetermined low speed maximumdesired operating time (e.g., tl used in act 111). Further, in a numberof embodiments, the predetermined high speed minimum desired operatingtime (e.g., th used in act 118) may be less than the predetermined highspeed maximum desired operating time (e.g., thh used in act 109). Forinstance, the predetermined high speed minimum desired operating time(e.g., th used in act 118) may be about 15 minutes, the predeterminedlow speed maximum desired operating time (e.g., tl used in act 111) maybe about 60 minutes, and the predetermined high speed maximum desiredoperating time (e.g., thh used in act 109) may be about 90 minutes, asexamples.

Method 10 illustrated in FIG. 1 may be performed by an air conditioningunit that is not a heat pump, or by a heat pump operating in a coolingmode (e.g., operating as an air conditioning unit). FIG. 2 illustrates asimilar method, method 20, being performed by a heat pump operating in aheating mode. In method 20, however, TL (e.g., of act 219) may be about30 degrees F., and TH (e.g., of act 212) may also be about 30 degrees F.In addition, in acts 212 and 219 of method 20, the greater than sign, orless than sign, is reversed from corresponding acts 112 and 119 ofmethod 10. Various methods described herein may be performed either in aheating mode or in a cooling mode.

FIGS. 3-6 illustrate examples of methods that use a two-stage thermostatto control an HVAC unit. Specifically, FIG. 3 illustrates method 30 thatuses a two-stage thermostat to control an HVAC unit operating in acooling mode, when stage one is demanded by the thermostat, and FIG. 4illustrates method 40 that uses a two-stage thermostat to control anHVAC unit operating in a cooling mode, when stage two is demanded by thethermostat. As another example, method 30 and method 40 may be combinedto provide a method that uses a two-stage thermostat to control an HVACunit operating in a cooling mode, when either stage one or stage two isdemanded by the thermostat.

Moreover, FIG. 5 illustrates method 50 that uses a two-stage thermostatto control an HVAC unit operating in a heating mode, when stage one isdemanded by the thermostat, and FIG. 6 illustrates method 60 that uses atwo-stage thermostat to control an HVAC unit operating in a heatingmode, when stage two is demanded by the thermostat. As another example,method 50 and method 60 may be combined to provide a method that uses atwo-stage thermostat to control an HVAC unit operating in a heatingmode, when either stage one or stage two is demanded by the thermostat.As yet another example, methods 30, 40, 50, and 60 may be combined toprovide a method that uses a two-stage thermostat to control an HVACunit operating in either a cooling mode or a heating mode, when eitherstage one or stage two is demanded by the thermostat.

Specifically, FIGS. 3-6 illustrate various methods of controlling anHVAC unit (e.g., having a compressor), that operate the compressor atmultiple compressor speeds, the multiple compressor speeds including anL low speed, an L mid speed, an L high speed, an H high speed, and aboost speed. In such embodiments, the HVAC unit (e.g., the controller ofthe HVAC unit) may be configured to operate the compressor using asignal from a two-speed or two-stage thermostat, for example, and toselect a current compressor speed from the multiple compressor speeds.

In the embodiment illustrated, method 30 includes, for example, at leastcertain acts, which include, for example, when a current run signal isreceived from the thermostat (e.g., in act 301), starting the compressor(e.g., in act 303 or 304), and evaluating whether the thermostat iscalling for stage one or stage two. If the thermostat is calling forstage one (e.g., detected in act 301), method 30 includes an act ofevaluating whether the thermostat called for stage two after a start ofan immediate prior run (e.g., in act 315 or 330), and if the thermostatcalled for stage two after the start of the immediate prior run (e.g.,during the immediate prior run), the method includes operating thecompressor at the L High speed during the current run signal (e.g., act331 and 304).

Further, if the thermostat is calling for stage one, and if thethermostat has not called for stage two since before the immediate priorrun (e.g., determined in act 315 or 330), the method includes an act ofevaluating whether the compressor speed changed during the immediateprior run (e.g., determined in act 315 or 330, for instance, wherein theimmediate prior run had a prior run final compressor speed and a priorrun time). If the compressor speed changed during the immediate priorrun, the method includes operating the compressor at the prior run finalcompressor speed during the current run signal (e.g., in act 322 or304). Thus, if the speed changed during the prior run, then the unit isoperated (at least initially) during the current run at the same speedas the end of the prior run.

Furthermore, if the thermostat is calling for stage one (e.g.,determined in act 301), if the thermostat has not called for stage twosince before the immediate prior run (e.g., determined in act 330), andif the compressor speed did not change during the immediate prior run(e.g., determined in act 315), method 30 includes an act of evaluatingwhether the prior run final compressor speed was the L low speed, the Lmid speed, or the L high speed (e.g., act 316). If the prior run finalcompressor speed was the L mid speed (e.g., determined in act 316),method 30 includes evaluating whether the prior run time (e.g., RT) wasless than a predetermined L mid speed minimum desired operating time(e.g., in act 318, for instance, 20 minutes). If the prior run time wasless than the predetermined L mid speed minimum desired operating time(e.g., determined in act 318), the method includes operating thecompressor at the L low speed during the current run signal (e.g., act325 and 304).

Even further, if the thermostat is calling for stage one (e.g.,determined in act 301), if the thermostat has not called for stage twosince before the immediate prior run (e.g., determined in act 315 or330), if the compressor speed did not change during the immediate priorrun (e.g., determined in act 315), and if the prior run final compressorspeed was the L high speed (e.g., determined in act 316), method 30includes an act of evaluating whether the prior run time was less than apredetermined L high speed minimum desired operating time (e.g., act328). If the prior run time (e.g., RT) was less than the predetermined Lhigh speed minimum desired operating time (e.g., 20 minutes, asdetermined in act 328), method 30 includes an act of operating thecompressor at the L mid speed during the current run signal (e.g., act327 and 304).

In FIG. 4, if the thermostat is calling for stage two (e.g., determinedin act 401), and if the thermostat did not call for stage two during theimmediate prior run (e.g., determined in act 415), method 40 includes anact of operating the compressor at the H high compressor speed duringthe current run signal (e.g., act 423 and 404). Still further, method 30includes measuring a current speed operating time during the current runsignal (e.g., act 306), and if the current compressor speed is the L lowspeed (e.g., determined in act 308), and if the current speed operatingtime is greater than a predetermined L low speed maximum desiredoperating time (e.g., determined in act 311), method 30 includes an actof increasing the compressor speed to the L mid speed during the currentrun signal (e.g., in act 313). Further, if the current compressor speedis the L mid speed (e.g., determined in act 308), and if the currentspeed operating time is greater than a predetermined L mid speed maximumdesired operating time (e.g., determined in act 309, for example, 60minutes), method 30 includes an act of increasing the compressor speedto the L high speed during the current run signal (e.g., act 310).Turning to FIG. 4, in some embodiments, if the current compressor speedis the H high speed (e.g., determined in act 408), and if the currentspeed operating time is greater than a predetermined H high speedmaximum desired operating time (e.g., determined in act 409), method 40includes increasing the compressor speed to the boost speed during thecurrent run signal (e.g., in act 413). In a number of embodiments, afterthe current run signal is no longer received from the thermostat (e.g.,in act 307, 407), such a method may further include acts of stopping thecompressor and repeating the above acts when the run signal is restored(e.g., in act 301, or 401).

In certain embodiments, a method includes, for example, when the currentrun signal is first received from the thermostat (e.g., in act 301, ordetermined in act 302), acts of starting the compressor, ramping thecompressor up to a start speed, and operating the compressor for apredetermined desired start time at a particular start speed (e.g., inact 314). In some embodiments, for example, the start speed is alwayssubstantially the same, for instance, regardless of the prior run finalcompressor speed. Further, in a number of embodiments, the HVAC unit hasa variable-speed drive for the compressor, and the HVAC unit operatesthe compressor at only a limited whole number of steady compressorspeeds. The steady compressor speeds may include, for example, the L lowspeed, the L mid speed, the L high speed and the H high speed.

In particular embodiments, the L mid speed may be higher than the L lowspeed, the L high speed may be higher than the L mid speed, the H highspeed may be higher than the L high speed, and the boost speed may behigher than the H high speed, for example. In different embodiments, theboost speed may also be one of the limited number of steady compressorspeeds, or in some embodiments, the boost speed may change (e.g.,depending on the outdoor temperature parameter or the temperature of theoutdoor coil). In other words, some embodiments, the method may includean act of varying the boost speed as a function of the outdoortemperature parameter.

In certain embodiments, the method includes, for example, operating thecompressor at no steady speeds other than the L low speed, the L midspeed, the L high speed, the H high speed, the boost speed, and thestart speed. In method 30, for example, the start speed (e.g., run inact 314) is the L mid speed. In other embodiments, however, the startspeed may be the L low speed, the L high speed, between the L low speedand the L mid speed, between the L low speed and the L high speed, orbetween the L mid speed and the L high speed, as other examples. Incertain embodiments, the start speed (e.g., run in act 314)

In some embodiments, the HVAC unit may have a two-speed indoor air fan,for example, configured to operate at a low speed and at a high speed,and the method may include, for instance, operating the indoor air fanat the low speed when the compressor is operating at the L low speed,and operating the indoor air fan at the low speed when the compressor isoperating at the L mid speed. Such a method may also include operatingthe indoor air fan at the high speed when the compressor is operating atthe H high speed, and operating the indoor air fan at the high speedwhen the compressor is operating at the boost speed. In someembodiments, the indoor air fan may be operated at the low speed whenthe compressor is operating at the L high speed. On the other hand, inother embodiments, the indoor air fan may be operated at the high speedwhen the compressor is operating at the L high speed.

Further, in some embodiments, such a method may further include, forexample, if the compressor speed did not change during the immediateprior run (e.g., determined in act 315), evaluating whether an outdoortemperature parameter is beyond a first threshold (e.g., act 319 or 321,for example, above 100 degrees F.). If the outdoor temperature parameteris beyond the first threshold, such a method (e.g., 30) may includeoperating the compressor at a higher speed during the current run signal(e.g., at the L high speed, in act 323, or at the L mid speed, in act327). In particular embodiments, the HVAC unit has an outdoor coil andthe outdoor temperature parameter is a temperature of the outdoor coil.In other embodiments, the outdoor temperature parameter may be outsideair temperature, or a pressure dependent on the outdoor temperature,such as condenser pressure, as examples.

Moreover, in some embodiments, such a method may further include, forexample, if the thermostat is calling for stage two, if the thermostatcalled for stage two during the immediate prior run (e.g., determined inact 330), and if the compressor speed did not change during stage two ofthe immediate prior run (e.g., as determined in act 415), an act ofoperating the compressor at the H high speed during the current runsignal (e.g., acts 423 and 404), in this embodiment, regardless of theoutdoor temperature parameter.

In some methods, if the thermostat is calling for stage two, if thethermostat called for stage two during the immediate prior run, and ifthe compressor speed changed (e.g., determined in act 415) during stagetwo of the immediate prior run (e.g., from H high to the boost speed),the method includes an act of operating the compressor at the boostspeed during the current run signal (e.g., act 422). In someembodiments, this may be done, for example, without first operating thecompressor at the H high speed for the predetermined H high speedmaximum desired operating time (e.g., through act 409 and 413). Further,in some embodiments, if the thermostat is calling for stage two, if thethermostat called for stage two during the immediate prior run, and ifthe compressor speed did not change during stage two of the immediateprior run (e.g., determined in act 415), the method (e.g., method 40)includes operating the compressor (e.g., at least initially) at the Hhigh speed during the current run signal (e.g., in act 423). Inparticular embodiments, for instance, the act of operating thecompressor during the current run signal at the H high speed may beperformed regardless of the prior run time.

Methods 50 and 60 shown in FIGS. 5 and 6 are similar to methods 30 and40 except that the HVAC unit is operating in a heating mode rather thana cooling mode. In method 50, LHL and LTH may be 30 degrees F., Ltl maybe 60 minutes, Lth may be 20 minutes, and tw may be two minutes, orabout such values, as examples. In method 60, HTH may be 25 degrees F.,Htl may be 60 minutes, Hth may be 20 minutes, and tw may be two minutes,or about such values, as examples.

The appropriate acts of methods 30, 40, 50, and 60 may be repeated orcycled through at regular intervals of time, for example (e.g., tw inact 305 or 405). Such an interval may be (e.g., tw) every two (2)minutes, for example. Further, the run times used, (e.g., in acts 306,309, 311, 318, and 409) may be a time at a particular compressor speed,rather than a total run time of the compressor at different speeds.Further, some methods apply to either single stage thermostat control,or two-stage thermostat control. In fact, some embodiments may apply toother numbers of stages of thermostats, such as three stages or fourstages, as examples. Such methods may include acts from various of themethods shown in the drawings or described herein, as examples.

Although, FIGS. 3-6 illustrate various methods of controlling an HVACunit that operate the compressor at multiple compressor speeds includingan L low speed, an L mid speed, an L high speed, an H high speed, and aboost speed, other embodiments may have a different number of compressorspeeds. For example, in a number of embodiments, there may be additionalcompressor speeds besides these specific speeds. In particularembodiments, there may be additional stage one speeds, for instance. Forexample, in some embodiments, there may be multiple L mid speeds, forinstance, between the L low speed and the L high speed. For instance,different embodiments may have 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10different L mid speeds, for example, between the L low speed and the Lhigh speed. In some embodiments, multiple L mid speeds may be spaced(e.g., evenly or proportionally) between the L low and L high speeds,for example. In various such embodiments, the system, method, orcontroller may change between different L mid speeds similarly to thedescription herein of the changes between the L low, L mid, and L highspeeds, for example.

Furthermore, various embodiments include methods of controlling an airconditioning unit or HVAC unit, for example, to reduce the use ofelectricity while maintaining space temperature within a desired range.Such a method may include, for example, certain acts, which may beperformed, for example, in the order indicated. Such acts may include,in a number of embodiments, receiving an on-signal from a thermostatlocated within the space (e.g., act 101, 201, 301, 401, 501, or 601),operating the unit at an operating speed (e.g., 103, 104, 203, 204, 303,304, 403, or 404), measuring how long the unit operates (e.g., 106, 206,306, or 406), increasing the operating speed (e.g., act 110, 113, 210,213, 310, or 313), receiving an off-signal (e.g., in act 107, 207, 307,or 407), and stopping operation of the unit. Such acts may also includereceiving another on-signal from the thermostat (e.g., act 101, 201,301, 401, 501, or 601), setting the compressor speed (e.g., in act 122,123, 322, 323, 327, 331, 422, or 423) returning to the act of measuringhow long the unit operates (e.g., 106, 206, 306, or 406), and repeatingthat act and the acts stated above that follow.

In particular, the act of operating the unit at an operating speed(e.g., 103, 104, 203, 204, 303, 304, 403, or 404) may include running acompressor motor driving a compressor at a compressor speed, and runningan (e.g., evaporator) fan motor at a blower speed. The fan motor maydrive an evaporator fan, for example, that moves indoor air through anevaporator and to the space. Further the act of operating the unit mayinclude running an outdoor or condenser fan motor at a condenser fanspeed, for example. The condenser fan motor may drive a condenser fanthat moves outdoor air through a condenser, for example.

Further, after the act of measuring how long the unit operates (e.g.,106, 206, 306, or 406), if the unit operates for longer than apredetermined maximum desired operating time (e.g., as determined in act109, 111, 309, 311, or 409, for example, 60 or 90 minutes), and if theunit is not already operating at a maximum operating speed (e.g.,boost), the method may include increasing the operating speed (e.g., inact 110, 113, 210, 213, 310, 313, or 413), which may include increasingthe compressor speed. In a number of embodiments, the act (e.g., afterreceiving the off-signal) of stopping operation of the unit, marks anend to an operating cycle having a final compressor speed at the timethe off-signal is received. Furthermore, the act of stopping operationmay include turning off the compressor motor, turning off the evaporatorfan motor, and turning off the condenser fan motor, for instance.

Furthermore, after receiving an (e.g., another) on-signal from thethermostat located within the space (e.g., in act 101, 201, 301, 401,501, or 601), various methods may include operating the unit at theoperating speed (e.g., act 104, 204, 304, or 404). If the compressorspeed was changed during an immediately previous operating cycle (e.g.,determined in act 115, 315, or 415), the compressor speed may be set atthe final compressor speed of the immediately previous operating cycle(e.g., act 122, 322, or 422). On the other hand, if the compressor speedwas not changed during the immediately previous operating cycle (e.g.,determined in act 115, 315, or 415), if the unit operated for less thana predetermined minimum desired operating time during the immediatelyprevious operating cycle (e.g., determined in act 118, 318, or 328) andif the unit did not operate at a minimum non-zero operating speed duringthe immediately previous operating cycle (e.g., low or L low), themethod may include decreasing the compressor speed from the finalcompressor speed of the immediately previous operating cycle (e.g., inact 125, 325, or 327).

Moreover, in a number of embodiments, if the compressor speed was notchanged during the immediately previous operating cycle (e.g.,determined in act 115, 315, or 415), if the unit operated for more thanthe predetermined minimum desired operating time during the immediatelyprevious operating cycle (e.g., evaluated in act 118, 318, or 328), andif the unit did not operate at a maximum non-zero operating speed duringthe immediately previous operating cycle (e.g., the boost speed, asdetermined in act 116 or 416), the compressor speed may be set at thefinal compressor speed of the immediately previous operating cycle(e.g., in act 123, 323, 325, or 327). After such acts, the method mayreturn to the act described above of measuring how long the unitoperates (e.g., act 106, 306, or 406), and repeating that act and theacts that follow.

In particular embodiments, the available non-zero compressor speeds mayinclude, or consist of, a low speed, a high speed, and a boost speed,and the low speed may be the minimum non-zero speed, while the boostspeed is the maximum speed. Method 10 in FIG. 1 is an example of such anembodiment. Further, in some embodiments, such a method may furtherinclude, for example, an act of measuring a coil temperature at thecondenser (e.g., act 106). In various embodiments, for example, the actof operating the unit at the operating speed may include, for instance,selecting a higher compressor speed (e.g., in acts 112 and 113) if thecoil temperature exceeds a first threshold temperature, and selecting alower compressor speed (e.g., act 112 to act 105) if the coiltemperature is below the first threshold temperature.

In other embodiments, however, temperature may not be measured (e.g., inact 106, 206, 306, or 406) or used to determine speed (e.g., in act 112,119, 212, 219, 312, 319, 321 or a combination thereof). Further, in anumber of embodiments, the control algorithm (e.g., method 10, 20, 30,40, 50, 60, or a combination thereof) may work satisfactorily withoutmeasuring or using an outdoor temperature. Some embodiments may omit act112, 119, 212, 219, 312, 319, 321 or a combination thereof, and someembodiments may omit measuring a temperature (e.g., in act 106, 206,306, or 406), or a combination thereof.

Further, in some embodiments, if the compressor speed was not changedduring the immediately previous operating cycle (e.g., determined in act115), and if the unit operated at the maximum non-zero operating speedduring the immediately previous operating cycle (e.g., the boost speed,for instance, as determined in act 116), the operating speed may bedecreased from the immediately previous operating cycle, includingdecreasing the compressor speed (e.g., to the high speed, for instance,in act 123). In some embodiments, this may occur, for example, even ifthe unit operated for longer than the predetermined minimum desiredoperating time (e.g., th, for instance, 15 minutes) during theimmediately previous operating cycle, or in certain embodiments, even ifthe unit operated for longer than the predetermined maximum desiredoperating time (e.g., thh, for instance, 90 minutes) during theimmediately previous operating cycle.

Other specific embodiments include various methods of controlling anHVAC unit and HVAC units that have controllers configured to performsuch methods. Such an HVAC unit may have a compressor that the HVACunit, or the controller therefore, operates at multiple compressorspeeds, for example, the multiple compressor speeds including a lowspeed, a high speed, and a boost speed. In a number of embodiments, theHVAC unit, or a controller therefore, is configured to operate thecompressor using a signal from a discrete-speed thermostat (e.g., asingle-stage, two-stage, or three-stage thermostat) and to select acurrent compressor speed from the multiple compressor speeds. Such amethod may include, for example, at least certain acts that may becommanded or performed, for instance, by a controller of the HVAC unit.

Such acts may include, for example, when a current run signal isreceived from the thermostat (e.g., act 101, 201, 301, 401, 501, or601), starting the compressor, and performing certain acts of evaluatingparticular conditions and operating the compressor or changing thecompressor speed based on those conditions. In particular, such acts mayinclude evaluating (e.g., in act 115, 315, 330, or 415) whether thecompressor speed changed during the immediate prior run. In a number ofembodiments, the immediate prior run may have had a prior run finalcompressor speed and a prior run time, which may be used in someembodiments (e.g., automatically, by the controller) to determine aspeed to operate the compressor, (e.g., at least initially) during acurrent run signal or on cycle). In various embodiments, for example, ifthe compressor speed changed (e.g., determined in act 115, 315, 330, or415) during the immediate prior run, such a method may include operatingthe compressor at the prior run final compressor speed during thecurrent run signal (e.g., act 122, 322, or 422).

Another such act involves evaluating whether the prior run finalcompressor speed was the high speed (e.g., act 116 or 316), and if theprior run final compressor speed was the high speed, and if thecompressor speed did not change during the immediate prior run,evaluating whether the prior run time was less than a predetermined highspeed minimum desired operating time (e.g., in act 118 or 328). Further,if the prior run time was less than the predetermined high speed minimumdesired operating time, the method may include operating the compressorat a lower speed during the current run signal (e.g., in act 125 and104, 325 and 304, or 327 and 304).

Another such act may include measuring a current speed operating timeduring the current run signal (e.g., in act 106, 206, 306, or 406), andif the current compressor speed is the low speed (e.g., determined inact 108 or 308), and if the current speed operating time is greater thana predetermined low speed maximum desired operating time (e.g.,determined in act 111 or 311), increasing the compressor speed duringthe current run signal (e.g., in act 113 or 313). Yet another such actinvolves measuring the current speed operating time during the currentrun signal, and if the current compressor speed is the high speed (e.g.,determined in act 108 or 408), and if the current speed operating timeis greater than a predetermined high speed maximum desired operatingtime (e.g., determined in act 109 or 409), increasing the compressorspeed during the current run signal (e.g., in act 110 or 413, forinstance, to the boost speed). Such a method may further include, afterthe current run signal is no longer received from the thermostat (e.g.,as determined in act 107, 307, or 407), stopping the compressor andrepeating the above acts when the run signal is restored (e.g., in act101, 301, or 401).

In a number of embodiments, the high speed is higher than the low speed,and the boost speed is higher than the high speed. Further, in someembodiments, the HVAC unit may be configured to operate the compressorusing a signal from a single-speed thermostat. Method 10 in FIG. 1 is anexample of such an embodiment. In this embodiment, method 10 furtherincludes, for instance, act 116 of evaluating whether the prior runfinal compressor speed was the boost speed. Moreover, if the prior runfinal compressor speed was the boost speed, and if the compressor speeddid not change during the immediate prior run (e.g., determined in act115), method 10 includes operating the compressor at the high speed(e.g., in act 123 and 104) during the current run signal, for example,regardless of the prior run time (e.g., RT). Other embodiments maydiffer in this regard. Other embodiments, for example, may repeatoperation at the boost speed (e.g., in subsequent run signals), forinstance, until the prior run time drops below a predetermined boostspeed minimum desired operating time. In some such embodiments, thepredetermined high speed minimum desired operating time may be more thanthe predetermined boost speed minimum desired operating time, however.

FIGS. 3-6 illustrate other embodiments wherein the low speed is an L lowspeed, the high speed may be an L high speed or an H high speed, and themultiple compressor speeds further include an L mid speed, and an L highspeed or an H high speed. In many such embodiments, the L mid speed ishigher than the L low speed, the L high speed is higher than the L midspeed, the H high speed is higher than the L high speed, and the boostspeed is higher than the H high speed, for example. Further, the HVACunit may be configured to operate the compressor using a signal from atwo-speed or two-stage thermostat. Such methods may include acts ofevaluating whether the thermostat is calling for stage one or stage two(e.g., in acts 301 and 401), and if the thermostat is calling for stageone (e.g., determined in act 301), evaluating whether the thermostatcalled for stage two after a start of an immediate prior run (e.g., act315 or 330). Further, if the thermostat called for stage two after thestart of the immediate prior run (e.g., determined in act 330), themethod may include operating the compressor at the L High speed (e.g.,in act 331) during the current run signal.

Moreover, in some embodiments, if the thermostat is calling for stagetwo, and if the thermostat did not call for stage two during theimmediate prior run, the method may include operating the compressor atthe H high compressor speed during the current run signal. Even further,in some embodiments, if the thermostat is calling for stage two (e.g.,determined in act 401), if the thermostat called for stage two duringthe immediate prior run, and if the compressor speed changed duringstage two of the immediate prior run (e.g., determined in act 415), themethod includes operating the compressor at the boost speed during thecurrent run signal (e.g., act 422 and 404).

Such methods may also include measuring the current speed operating timeduring the current run signal (e.g., in act 306 or 406). In a number ofembodiments, if the current compressor speed is the L mid speed (e.g.,determined in act 308) and if the current speed operating time (e.g.,RT) is greater than a predetermined L mid speed maximum desiredoperating time (e.g., Ltl, for instance, 60 minutes, for example,determined in act 309), the method includes increasing the compressorspeed to the L high speed during the current run signal (e.g., in act310). Such a method may also include measuring the current speedoperating time during the current run signal (e.g., in act 406 shown inFIG. 4), and if the current compressor speed is the H high speed (e.g.,determined in act 408), and if the current speed operating time (e.g.,RT) is greater than a predetermined H high speed maximum desiredoperating time (e.g., Htl, for instance, 60 minutes, for example,determined in act 409) increasing the compressor speed to the boostspeed during the current run signal (e.g., in act 413).

In a number of embodiments, the HVAC unit may have a two-speed indoorair fan configured to operate at a low speed and at a high speed, andthe method includes, for instance, operating the indoor air fan at thelow speed when the compressor is operating at the L low speed, andoperating the indoor air fan at the low speed when the compressor isoperating at the L mid speed. Such a method may also include, forexample, operating the indoor air fan at the high speed when thecompressor is operating at the H high speed, and operating the indoorair fan at the high speed when the compressor is operating at the boostspeed. In some embodiments, the indoor air fan may be operated at thelow speed when the compressor is operating at the L high speed, while inother embodiments, the indoor air fan may be operated at the high speedwhen the compressor is operating at the L high speed.

Furthermore, in certain embodiments, if the thermostat is calling forstage two (e.g., determined in act 401), if the thermostat called forstage two during the immediate prior run, and if the compressor speeddid not change during stage two of the immediate prior run (e.g.,determined in act 415), the method includes operating the compressor atthe H high speed (e.g., in act 423 and 404) during the current runsignal. In some embodiments, this act of operating the compressor duringthe current run signal at the H high speed (e.g., in act 423 and 404)may be performed regardless of the prior run time (e.g., RT), forexample. Such acts may be performed, for example, by a controller of anHVAC unit, and various embodiments include an HVAC unit with acontroller configured to perform such acts. Other embodiments maydiffer, examples of which are described herein.

FIGS. 3-6 and methods 30, 40, 50, and 60, also illustrate examples ofmethods of controlling an HVAC unit (e.g., having a compressor that theHVAC unit operates at multiple compressor speeds) using a two-stagethermostat in which the multiple compressor speeds include at least twodifferent non-zero compressor speeds for stage one, and at least onenon-zero compressor speed for stage two. In the embodiment illustrated,the at least two different non-zero compressor speeds for stage oneinclude the L low, L mid, and L high speeds, and the at least onenon-zero compressor speed for stage two includes the H high and Boost(boost) speeds. Other embodiments, however, may have a different numberof different non-zero compressor speeds for stage one, a differentnumber of non-zero compressor speed for stage two, or both. For example,other embodiments may have 2, 4, 5, 6, 7, 8, 9, 10, 11, or 12 differentnon-zero compressor speeds for stage one, 1, 3, 4, 5, 6, 7, 8, 9, or 10non-zero compressor speed for stage two, or a combination thereof, asexamples.

In a number of embodiments, the at least two different non-zerocompressor speeds for stage one may include a highest compressor speedfor stage one (e.g., L high) and a lowest compressor speed for stage one(e.g., L low). Moreover, in various embodiments, the at least onenon-zero compressor speed for stage two may includes a highestcompressor speed for stage two (e.g., the boost speed). In certainembodiments, where there is only one non-zero compressor speed for stagetwo, the highest compressor speed for stage two (as used herein) is theonly non-zero compressor speed for stage two. Further, in methods 30,40, 50, and 60, as described, the HVAC unit is configured to operate thecompressor using a signal from a two-stage thermostat (e.g., athermostat configured for a two-speed discrete-speed HVAC unit) and toselect a current compressor speed from the multiple compressor speeds(e.g., the at least two different non-zero compressor speeds for stageone and the at least one non-zero compressor speed for stage two).

In the embodiments illustrated, methods 30, 40, 50, and 60 include, forexample, at least certain acts that include, when a current run signalis received from the thermostat (e.g., in act 301, 401, 501, or 601, ordetermined in act 302), starting the compressor, and performing certainacts of evaluating particular conditions and operating the compressor,selecting the compressor speed, or changing the compressor speed basedon those conditions. In particular, such acts may include evaluating(e.g., determined in act 115, 315, or 415) whether the compressor stagechanged (e.g., from stage one to stage two) during the immediate priorrun. In a number of embodiments, the immediate prior run may have had aprior run final compressor speed and a prior run time, which may havebeen stored, for example, in digital memory. This act of evaluatingwhether the compressor stage changed during the immediate prior run mayinvolve, for instance, recording whether the compressor stage changedduring the immediate prior run, and accessing this information to makedecisions, for example, concerning the compressor speed.

Further, in the embodiments illustrated, if the compressor stage changed(e.g., determined in act 115, 315, or 415, for instance, from stage oneto stage two) during the immediate prior run, the method includesoperating the compressor at the highest compressor speed for stage one(e.g., the L High speed; for example, in act 331 and 304) during thecurrent run signal. The compressor may be operated, for example, at thehighest compressor speed for stage one initially or after operating thecompressor at a start speed, for instance. As described herein, however,in some embodiments, the compressor speed may be increased further, forexample, after a period of time.

On the other hand, if the compressor stage did not change (e.g., stayedat stage one) during the immediate prior run (e.g., determined in act115, 315, or 415), and if the prior run final compressor speed was notthe lowest compressor speed for stage one (e.g., L Low), various methodsmay include evaluating (e.g., in act 318 or 328) whether the prior runtime was less than a predetermined minimum desired operating time (e.g.,Lth or 20 minutes), for example, for the prior run final compressorspeed. For this purpose, the prior run time, or whether the prior runtime was less than the predetermined minimum desired operating time mayhave been recorded, and this information may be accessed to make thedetermination or selection of the compressor speed, for example.

In some embodiments, the act of evaluating whether the prior run timewas less than a predetermined minimum desired operating time may beperformed only if the compressor stage did not change during theimmediate prior run, and if the prior run final compressor speed was notthe lowest compressor speed for stage one. In other embodiments,however, the act of evaluating whether the prior run time was less thana predetermined minimum desired operating time may be performedregardless of whether the compressor stage changed during the immediateprior run, regardless of whether the prior run final compressor speedwas the lowest compressor speed for stage one, or both. In embodimentswherein the act of evaluating whether the prior run time was less than apredetermined minimum desired operating time is performed regardless ofthese other conditions, the other conditions may be used to determinethe compressor speed, however.

In various embodiments, the predetermined minimum desired operating timemay be the same for different speeds, may be different for stage onethan for stage two (e.g., Lth and Hth), may be different for eachdifferent speed, or may be different for some speeds and the same forothers. In particular embodiments, for example, the predeterminedminimum desired operating time (e.g., for a particular compressor speed,Lth, or Hth) may be about 10, 15, 20, 25, 30, 35, or 40 minutes, asexamples.

If (e.g., determined in act 318 or 328) the prior run time was greaterthan the predetermined minimum desired operating time (e.g., Lth, forinstance, for the prior run final compressor speed), and, if thecompressor stage did not change (e.g., stayed at stage one) during theimmediate prior run, the method may include operating (e.g., in act 304)the compressor at a speed during the current run signal that is equalto, or the same as, the prior run final compressor speed. For example,if the prior run final compressor speed was the L high speed, then thecompressor may be operated (e.g., at least initially, or after operationat a start speed) during the current run signal at the L high speed.Similarly, if the prior run final compressor speed was the L mid speed,then the compressor may be operated (e.g., at least initially, or afteroperation at a start speed) during the current run signal at the L midspeed. Moreover, if the prior run final compressor speed was the L lowspeed, then the compressor may be operated (e.g., at least initially, orafter operation at a start speed) during the current run signal at the Llow speed. Thus, in this embodiment, the compressor speed is selected(at least initially) to be the same as the prior run if the prior runtime was greater than the predetermined minimum desired operating time.

In contrast, in this particular embodiment, if (e.g., in act 318 or 328)the prior run time was less than the predetermined minimum desiredoperating time (e.g., Lth, for instance, for the prior run finalcompressor speed), if the compressor stage did not change (e.g., stayedat stage one) during the immediate prior run, and if the prior run finalcompressor speed was not the lowest compressor speed for stage one(e.g., L Low), the method may include operating the compressor at aspeed during the current run signal that is lower, for example, one steplower, than the prior run final compressor speed. For example, if theprior run final compressor speed was the L high speed, then thecompressor may be operated (e.g., at least initially, or after operationat a start speed) during the current run signal at the L mid speed.Similarly, if the prior run final compressor speed was the L mid speed,then the compressor may be operated (e.g., at least initially, or afteroperation at a start speed) during the current run signal at the L lowspeed. Thus, under these circumstances, in this embodiment, thecompressor speed is reduced from the prior run compressor speed, whichmay increase the run time, increase efficiency, reduce noise, provide amore stable temperature, or a combination thereof. As used herein,changing the compressor speed by one step, means raising or lowering thecompressor speed to the closest speed (above or below) of the multiplecompressor speeds that the HVAC unit or controller is configured toselect from.

Another act that is illustrated, and that is found in some embodiments,involves measuring a current speed operating time during the current runsignal (e.g., in act 306 or 406), and if the current compressor speed isnot already the highest compressor speed for stage two (e.g., the boostspeed, for example, determined in act 308 or 408)), and if the currentspeed operating time is greater than a predetermined maximum desiredoperating time (e.g., Ltl or Htl, for instance, in act 309, 311, or409), for example, for the current speed (e.g., L low, L mid, or Hhigh), increasing the compressor speed, for instance, by one step (e.g.,in act 310, 313, or 413) during the current run signal.

In the embodiment illustrated, if the compressor speed is the L highspeed (e.g., evaluated in act 308) or the highest compressor speed forstage one, the compressor speed does not increase further (e.g., to astage two speed, such as H high) until and unless the thermostat callsfor stage two. In other embodiments, on the other hand, the compressorspeed may increase further (e.g., by one step, or to a stage two speed,such as H high) if a maximum desired operating time (e.g., for theparticular current speed or for multiple or all of the speeds) isreached at the highest compressor speed for stage one (e.g., L high). Insome embodiments, this speed increase may take place even if thethermostat does not call for stage two.

In various embodiments, the predetermined maximum desired operating time(e.g., Ltl or Htl) may be the same for different speeds, may bedifferent for stage one and stage two (e.g., Ltl and Htl), may bedifferent for each different speed, or may be different for some speedsand the same for others, as examples. In particular embodiments, forinstance, the predetermined maximum desired operating time (e.g., for aparticular compressor speed, Ltl, or Htl) may be about 30, 35, 40, 45,50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, or 120minutes, as examples. Further, in the embodiment illustrated, the methodfurther includes, after the current run signal is no longer receivedfrom the thermostat (e.g., determined in act 307 or 407), stopping thecompressor and repeating the above acts when the run signal is restored(e.g., in act 301, 401, 501, or 601).

In a number of embodiments, the highest compressor speed for stage two(e.g., the boost speed) is higher than (or in particular embodiments,higher than or equal to) the highest compressor speed for stage one(e.g., L high). Further, in a number of embodiments, the highestcompressor speed for stage one (e.g., L high) is higher than the lowestcompressor speed for stage one (e.g., L low). In the particularembodiment illustrated, L mid is higher than L low, L high is higherthan L mid, H high is higher than L high, and Boost is higher than Hhigh. Other embodiments may be similar or may differ.

In various embodiments, the HVAC unit may have a two-speed indoor airfan configured to operate at a low speed and at a high speed. Further,the method may include, for instance, operating the indoor air fan atthe low speed when the compressor is operating at one of the at leasttwo different non-zero compressor speeds for stage one. Even further, incertain embodiments, such a method may include for example, operatingthe indoor air fan at the high speed when the compressor is operating atthe at least one non-zero compressor speed for stage two.

Further, in certain embodiments, the HVAC unit has an outdoor air fanthat operates at multiple non-zero speeds. These speeds may include, forexample, at least a first outdoor air fan speed and a second outdoor airfan speed. In different embodiments, the outdoor air fan may have a twoor three speed motor, for example, or may have a variable-speed motor,or have a variable-speed drive, and may operate at different (e.g.,steady) speeds, for instance, at different compressor speeds. In anumber of embodiments, for example, the method may include operating theoutdoor air fan at the first outdoor air fan speed when the compressoris operating at the lowest compressor speed for stage one. Further,various embodiments may include operating the outdoor air fan at thesecond outdoor air fan speed when the compressor is operating at thehighest compressor speed for stage two. Even further, in a number ofembodiments, the second outdoor air fan speed may be greater than thefirst outdoor air fan speed.

Moreover, in some embodiments, the method may include operating theoutdoor air fan at the first outdoor air fan speed when the compressoris operating at the highest compressor speed for stage one. In contrast,in some embodiments, the method may include operating the outdoor airfan at the second outdoor air fan speed when the compressor is operatingat the highest compressor speed for stage one. On the other hand, inother embodiments, the method may include operating the outdoor air fanat a third outdoor air fan speed when the compressor is operating at thehighest compressor speed for stage one. The third outdoor air fan speedmay be greater than the first outdoor air fan speed but less than thesecond outdoor air fan speed, for example. In certain embodiments, themethod may include operating the outdoor air fan at a different outdoorair fan speed for each different compressor speed, as another example.

Various methods may further include acts of obtaining, providing, ormaking various components described herein or known in the art. Otherembodiments include a controller configured to perform a methoddescribed herein, an HVAC unit including such a controller, an HVACsystem that includes such a controller or unit, or a building thatincludes such an HVAC system. Further embodiments include variouscomputer-readable storage media that may include, for example,computer-readable instructions to perform a method described herein.Such media may be or include, for example, a disc, random access memory(RAM), read only memory (ROM), programmable read only memory (PROM),erasable programmable read only memory (EPROM), electronically erasableprogrammable read only memory (EEPROM), flash memory, or the like. Otherembodiments include various computers programmed to perform a methoddescribed herein, and computer software including, for example,instructions to perform a method described herein.

Various methods in accordance with different embodiments include acts ofselecting, making, positioning, or using certain components, asexamples. Other embodiments may include performing other of these actson the same or different components, or may include fabricating,assembling, obtaining, providing, ordering, receiving, shipping, orselling such components, or other components described herein or knownin the art, as other examples. Further, various embodiments includevarious combinations of the components, features, and acts describedherein or shown in the drawings, for example. Further, particularembodiments include various means for accomplishing one or more of theparticular functions described herein or apparent from the structuredescribed. Other embodiments may be apparent to a person of ordinaryskill in the art having studied this document.

1. A method of controlling an air conditioning unit to reduce the use ofelectricity while maintaining space temperature within a desired range,the method comprising in the following order at least the acts of:receiving an on-signal from a thermostat located within the space;operating the unit at an operating speed wherein the act of operatingthe unit includes running a compressor motor driving a compressor at acompressor speed, running an evaporator fan motor at a blower speed, theevaporator fan motor driving an evaporator fan that moves indoor airthrough an evaporator and to the space, and running a condenser fanmotor at a condenser fan speed, the condenser fan motor driving acondenser fan that moves outdoor air through a condenser; measuring howlong the unit operates; if the unit operates for longer than apredetermined maximum desired operating time, and if the unit is notalready operating at a maximum operating speed, increasing the operatingspeed, wherein the act of increasing the operating speed includesincreasing the compressor speed; receiving an off-signal from thethermostat located within the space; after receiving the off-signal,stopping operation of the unit, wherein the act of stopping operation ofthe unit marks an end to an operating cycle having a final compressorspeed at the time the off-signal is received, and wherein the act ofstopping operation includes turning off the compressor motor, turningoff the evaporator fan motor, and turning off the condenser fan motor;receiving an on-signal from the thermostat located within the space;operating the unit at the operating speed wherein: if the compressorspeed was changed during an immediately previous operating cycle, thecompressor speed is set at the final compressor speed of the immediatelyprevious operating cycle, if the compressor speed was not changed duringthe immediately previous operating cycle, and if the unit operated forless than a predetermined minimum desired operating time during theimmediately previous operating cycle, and if the unit did not operate ata minimum non-zero operating speed during the immediately previousoperating cycle, decreasing the compressor speed from the finalcompressor speed of the immediately previous operating cycle, and if thecompressor speed was not changed during the immediately previousoperating cycle, if the unit operated for more than the predeterminedminimum desired operating time during the immediately previous operatingcycle, and if the unit did not operate at a maximum non-zero operatingspeed during the immediately previous operating cycle, the compressorspeed is set at the final compressor speed of the immediately previousoperating cycle; and if the compressor speed was not changed during theimmediately previous operating cycle, and if the unit operated at themaximum non-zero operating speed during the immediately previousoperating cycle, the operating speed is decreased from the immediatelyprevious operating cycle, including decreasing the compressor speed,even if the unit operated for longer than the predetermined minimumdesired operating time during the immediately previous operating cycle;and returning to the act above of measuring how long the unit operates,and repeating that act and the acts that follow.
 2. The method of claim1 wherein available non-zero compressor speeds consist of a low speed, ahigh speed, and a boost speed, wherein the low speed is the minimumnon-zero speed and the boost speed is the maximum speed.
 3. The methodof claim 1 further comprising an act of measuring a coil temperature atthe condenser.
 4. The method of claim 3 wherein the act of operating theunit at the operating speed comprises selecting a higher compressorspeed if the coil temperature exceeds a first threshold temperature, andselecting a lower compressor speed if the coil temperature is below thefirst threshold temperature.
 5. A method of controlling an airconditioning unit to reduce the use of electricity while maintainingspace temperature within a desired range, the method comprising in thefollowing order at least the acts of: receiving an on-signal from athermostat located within the space; operating the unit at an operatingspeed wherein the act of operating the unit includes running acompressor motor driving a compressor at a compressor speed, running anevaporator fan motor at a blower speed, the evaporator fan motor drivingan evaporator fan that moves indoor air through an evaporator and to thespace, and running a condenser fan motor at a condenser fan speed, thecondenser fan motor driving a condenser fan that moves outdoor airthrough a condenser; measuring how long the unit operates; if the unitoperates for longer than a predetermined maximum desired operating time,and if the unit is not already operating at a maximum operating speed,increasing the operating speed, wherein the act of increasing theoperating speed includes increasing the compressor speed; receiving anoff-signal from the thermostat located within the space; after receivingthe off-signal, stopping operation of the unit, wherein the act ofstopping operation of the unit marks an end to an operating cycle havinga final compressor speed at the time the off-signal is received, andwherein the act of stopping operation includes turning off thecompressor motor, turning off the evaporator fan motor, and turning offthe condenser fan motor; receiving an on-signal from the thermostatlocated within the space; operating the unit at the operating speedwherein: if the compressor speed was changed during an immediatelyprevious operating cycle, the compressor speed is set at the finalcompressor speed of the immediately previous operating cycle, if thecompressor speed was not changed during the immediately previousoperating cycle, and if the unit operated for less than a predeterminedminimum desired operating time during the immediately previous operatingcycle, and if the unit did not operate at a minimum non-zero operatingspeed during the immediately previous operating cycle, decreasing thecompressor speed from the final compressor speed of the immediatelyprevious operating cycle, and if the compressor speed was not changedduring the immediately previous operating cycle, if the unit operatedfor more than the predetermined minimum desired operating time duringthe immediately previous operating cycle, and if the unit did notoperate at a maximum non-zero operating speed during the immediatelyprevious operating cycle, the compressor speed is set at the finalcompressor speed of the immediately previous operating cycle; and if thecompressor speed was not changed during the immediately previousoperating cycle, and if the unit operated at the maximum non-zerooperating speed during the immediately previous operating cycle, theoperating speed is decreased from the immediately previous operatingcycle, including decreasing the compressor speed, even if the unitoperated for longer than the predetermined maximum desired operatingtime during the immediately previous operating cycle; and returning tothe act above of measuring how long the unit operates, and repeatingthat act and the acts that follow.
 6. The method of claim 5 whereinavailable non-zero compressor speeds consist of a low speed, a highspeed, and a boost speed, wherein the low speed is the minimum non-zerospeed and the boost speed is the maximum speed.
 7. The method of claim 5further comprising an act of measuring a coil temperature at thecondenser.
 8. The method of claim 7 wherein the act of operating theunit at the operating speed comprises selecting a higher compressorspeed if the coil temperature exceeds a first threshold temperature, andselecting a lower compressor speed if the coil temperature is below thefirst threshold temperature.
 9. A method of controlling an HVAC unit,the HVAC unit having a compressor, wherein the HVAC unit operates thecompressor at multiple compressor speeds, the multiple compressor speedsincluding a low speed, a high speed, and a boost speed, wherein the highspeed is higher than the low speed, and the boost speed is higher thanthe high speed, and wherein the HVAC unit is configured to operate thecompressor using a signal from a single-speed thermostat and to select acurrent compressor speed from the multiple compressor speeds, the methodcomprising at least the acts of: when a current run signal is receivedfrom the thermostat, starting the compressor; evaluating whether thecompressor speed changed during the immediate prior run, wherein theimmediate prior run had a prior run final compressor speed and a priorrun time, and if the compressor speed changed during the immediate priorrun, operating the compressor at the prior run final compressor speedduring the current run signal; evaluating whether the prior run finalcompressor speed was the high speed, and if the prior run finalcompressor speed was the high speed, and if the compressor speed did notchange during the immediate prior run, evaluating whether the prior runtime was less than a predetermined high speed minimum desired operatingtime, and if the prior run time was less than the predetermined highspeed minimum desired operating time, operating the compressor at alower speed during the current run signal; evaluating whether the priorrun final compressor speed was the boost speed and if the prior runfinal compressor speed was the boost speed, and if the compressor speeddid not change during the immediate prior run, operating the compressorat the high speed during the current run signal regardless of the priorrun time; measuring a current speed operating time during the currentrun signal, and if the current compressor speed is the low speed and ifthe current speed operating time is greater than a predetermined lowspeed maximum desired operating time, increasing the compressor speedduring the current run signal; measuring the current speed operatingtime during the current run signal, and if the current compressor speedis the high speed and if the current speed operating time is greaterthan a predetermined high speed maximum desired operating time,increasing the compressor speed during the current run signal; and afterthe current run signal is no longer received from the thermostat,stopping the compressor and repeating the above acts when the run signalis restored.
 10. A method of controlling an HVAC unit, the HVAC unithaving a compressor, wherein the HVAC unit operates the compressor atmultiple compressor speeds, the multiple compressor speeds including anL low speed, an L mid speed, an L high speed, an H high speed and aboost speed, wherein the L mid speed is higher than the L low speed, theL high speed is higher than the L mid speed, the H high speed is higherthan the L high speed, and the boost speed is higher than the H highspeed, and wherein the HVAC unit is configured to operate the compressorusing a signal from a two-speed thermostat and to select a currentcompressor speed from the multiple compressor speeds, the methodcomprising at least the acts of: when a current run signal is receivedfrom the thermostat, starting the compressor; evaluating whether thecompressor speed changed during the immediate prior run, wherein theimmediate prior run had a prior run final compressor speed and a priorrun time, and if the compressor speed changed during the immediate priorrun, operating the compressor at the prior run final compressor speedduring the current run signal; evaluating whether the prior run finalcompressor speed was the L high speed, and if the prior run finalcompressor speed was the L high speed, and if the compressor speed didnot change during the immediate prior run, evaluating whether the priorrun time was less than a predetermined L high speed minimum desiredoperating time, and if the prior run time was less than thepredetermined L high speed minimum desired operating time, operating thecompressor at a lower speed during the current run signal; evaluatingwhether the thermostat is calling for stage one or stage two; if thethermostat is calling for stage one, evaluating whether the thermostatcalled for stage two after a start of an immediate prior run, and if thethermostat called for stage two after the start of the immediate priorrun, operating the compressor at the L High speed during the current runsignal; if the thermostat is calling for stage two, and if thethermostat did not call for stage two during the immediate prior run,operating the compressor at the H high compressor speed during thecurrent run signal; if the thermostat is calling for stage two, if thethermostat called for stage two during the immediate prior run, and ifthe compressor speed changed during stage two of the immediate priorrun, operating the compressor at the boost speed during the current runsignal; if the thermostat is calling for stage two, if the thermostatcalled for stage two during the immediate prior run, and if thecompressor speed did not change during stage two of the immediate priorrun, operating the compressor at the H high speed during the current runsignal regardless of the prior run time; measuring a current speedoperating time during the current run signal, and if the currentcompressor speed is the L low speed and if the current speed operatingtime is greater than a predetermined L low speed maximum desiredoperating time, increasing the compressor speed during the current runsignal; measuring the current speed operating time during the currentrun signal, and if the current compressor speed is the L high speed andif the current speed operating time is greater than a predetermined Lhigh speed maximum desired operating time, increasing the compressorspeed during the current run signal; measuring the current speedoperating time during the current run signal, and if the currentcompressor speed is the L mid speed and if the current speed operatingtime is greater than a predetermined L mid speed maximum desiredoperating time, increasing the compressor speed to the L high speedduring the current run signal; measuring the current speed operatingtime during the current run signal, and if the current compressor speedis the H high speed and if the current speed operating time is greaterthan a predetermined H high speed maximum desired operating time,increasing the compressor speed to the boost speed during the currentrun signal; and after the current run signal is no longer received fromthe thermostat, stopping the compressor and repeating the above actswhen the run signal is restored.
 11. The method of claim 10 wherein theHVAC unit has a two-speed indoor air fan configured to operate at a lowspeed and at a high speed, wherein the method comprises: operating theindoor air fan at the low speed when the compressor is operating at theL low speed; operating the indoor air fan at the low speed when thecompressor is operating at the L mid speed; operating the indoor air fanat the high speed when the compressor is operating at the H high speed;and operating the indoor air fan at the high speed when the compressoris operating at the boost speed.
 12. An HVAC unit comprising acompressor, wherein the HVAC unit operates the compressor at multiplecompressor speeds, the multiple compressor speeds including an L lowspeed, an L mid speed, an L high speed, an H high speed, and a boostspeed, wherein the HVAC unit comprises a controller configured tooperate the compressor using a signal from a two-speed thermostat and toselect a current compressor speed from the multiple compressor speeds,wherein the controller is configured to perform at least the acts of:when a current run signal is received from the thermostat, starting thecompressor; evaluating whether the thermostat is calling for stage oneor stage two; if the thermostat is calling for stage one, evaluatingwhether the thermostat called for stage two after a start of animmediate prior run, and if the thermostat called for stage two afterthe start of the immediate prior run, operating the compressor at the LHigh speed during the current run signal; if the thermostat is callingfor stage one, and if the thermostat has not called for stage two sincebefore the immediate prior run, evaluating whether the compressor speedchanged during the immediate prior run, wherein the immediate prior runhad a prior run final compressor speed and a prior run time, and if thecompressor speed changed during the immediate prior run, operating thecompressor at the prior run final compressor speed during the currentrun signal; if the thermostat is calling for stage one, if thethermostat has not called for stage two since before the immediate priorrun, and if the compressor speed did not change during the immediateprior run, evaluating whether the prior run final compressor speed wasthe L low speed, the L mid speed, or the L high speed, and if the priorrun final compressor speed was the L mid speed, evaluating whether theprior run time was less than a predetermined L mid speed minimum desiredoperating time, and if the prior run time was less than thepredetermined L mid speed minimum desired operating time, operating thecompressor at the L low speed during the current run signal; if thethermostat is calling for stage one, if the thermostat has not calledfor stage two since before the immediate prior run, if the compressorspeed did not change during the immediate prior run, and if the priorrun final compressor speed was the L high speed, evaluating whether theprior run time was less than a predetermined L high speed minimumdesired operating time, and if the prior run time was less than thepredetermined L high speed minimum desired operating time, operating thecompressor at the L mid speed during the current run signal; if thethermostat is calling for stage two, and if the thermostat did not callfor stage two during the immediate prior run, operating the compressorat the H high compressor speed during the current run signal; if thethermostat is calling for stage two, if the thermostat called for stagetwo during the immediate prior run, and if the compressor speed did notchange during stage two of the immediate prior run, the controllerperforms acts of operating the compressor at the H high speed during thecurrent run signal regardless of the prior run time; measuring a currentspeed operating time during the current run signal, and if the currentcompressor speed is the L low speed and if the current speed operatingtime is greater than a predetermined L low speed maximum desiredoperating time, increasing the compressor speed to the L mid speedduring the current run signal; measuring the current speed operatingtime during the current run signal, and if the current compressor speedis the L mid speed and if the current speed operating time is greaterthan a predetermined L mid speed maximum desired operating time,increasing the compressor speed to the L high speed during the currentrun signal; measuring the current speed operating time during thecurrent run signal, and if the current compressor speed is the H highspeed and if the current speed operating time is greater than apredetermined H high speed maximum desired operating time, increasingthe compressor speed to the boost speed during the current run signal;and after the current run signal is no longer received from thethermostat, stopping the compressor and repeating the above acts whenthe run signal is restored.
 13. The HVAC unit of claim 12 wherein thecontroller is configured so that when the current run signal is firstreceived from the thermostat, the controller performs acts of: startingthe compressor; ramping the compressor up to a start speed; andoperating the compressor for a predetermined desired start time at thestart speed; wherein the start speed is substantially the sameregardless of the prior run final compressor speed.
 14. The HVAC unit ofclaim 12 wherein the controller is configured so that if the compressorspeed did not change during the immediate prior run, the controllerperforms acts of: evaluating whether an outdoor temperature parameter isbeyond a first threshold; and if the outdoor temperature parameter isbeyond the first threshold, operating the compressor at a higher speedduring the current run signal.
 15. The HVAC unit of claim 14 wherein theHVAC unit has an outdoor coil and the outdoor temperature parameter is atemperature of the outdoor coil.
 16. The HVAC unit of claim 14 whereinthe controller is configured to perform an act of varying the boostspeed as a function of the outdoor temperature parameter.
 17. The HVACunit of claim 14 wherein the controller is configured so that if thethermostat is calling for stage two, if the thermostat called for stagetwo during the immediate prior run, and if the compressor speed did notchange during stage two of the immediate prior run, the controllerperforms an act of operating the compressor at the H high speed duringthe current run signal regardless of the outdoor temperature parameter.18. The HVAC unit of claim 12 wherein the HVAC unit has a variable-speeddrive for the compressor, wherein the HVAC unit operates the compressorat only a limited whole number of steady compressor speeds, wherein thesteady compressor speeds include the L low speed, the L mid speed, the Lhigh speed and the H high speed, and wherein the L mid speed is higherthan the L low speed, the L high speed is higher than the L mid speed,the H high speed is higher than the L high speed, and the boost speed ishigher than the H high speed.
 19. The HVAC unit of claim 12 wherein thecontroller is configured to operate the compressor at no steady speedsother than the L low speed, the L mid speed, the L high speed, the Hhigh speed, the boost speed, and a start speed.
 20. The HVAC unit ofclaim 12 wherein the HVAC unit has a two-speed indoor air fan configuredto operate at a low speed and at a high speed, and wherein thecontroller is configured to perform acts of: operating the indoor airfan at the low speed when the compressor is operating at the L lowspeed; operating the indoor air fan at the low speed when the compressoris operating at the L mid speed; operating the indoor air fan at thehigh speed when the compressor is operating at the H high speed; andoperating the indoor air fan at the high speed when the compressor isoperating at the boost speed.
 21. The HVAC unit of claim 12 wherein thecontroller is configured so that if the thermostat is calling for stagetwo, if the thermostat called for stage two during the immediate priorrun, and if the compressor speed changed during stage two of theimmediate prior run, the controller will perform an act of operating thecompressor at the boost speed during the current run signal withoutfirst operating the compressor at the H high speed for the predeterminedH high speed maximum desired operating time.